CA1287923C - Data acquisition module and method - Google Patents

Abstract

Abstract of the Disclosure A data acquisition apparatus includes two microcomputers interconnected by a shared dual access digital storage device. One microcomputer obtains the data related to the monitored condition, stores it in the digital storage device, and modifies a status word which is monitored by the other microcomputer. When the other microcomputer detects a change in the status word, it takes the data from the shared digital memory and moves it into its own memory for subse-quent use or transfer. The data acquisition apparatus also includes, in a preferred embodiment, analog switches and a digital to analog converter by which external analog devices can be controlled to change the monitored operation.

Description

DATA ACQUISITION MODULE ~ND METHOD
Backqround of the Invention This invention relates qenerally to apparatus and methods for acquiring data related to one or more detected characteristics and more particularly, but not by waY of limitation, to apparatus and methods for locally monitorinq a plurality of conditions of a process near the process and for making the data correspondinq to the conditions available to a location remote from the process.
To accurately control a process, several conditions or characteristics existinq throughout the process need to be monitored so that one knows whether the process is beinq performed as it should be. For example, durinq a cementinq operation at an oil or gas well site, a cement slurry is produced and pumped into the well. To monitor the quality o~ the slurry and its placement in the well, various pres-sures, flow rates and densities associated with the slurry and its flow need to be known. Such a process is carried out over a considerable physical area of the well site, and the conditions or characteristics to be known exist at various spaced locations throuqhout the process area, so that human observation of locally disposed gauqes or read-outs would not alone provide satisfactory monitoring of the job. Therefore, there is the need for an automated moni-toring system and method by which data representinq condi-tions or characteristics to be monitored can be collected and centrally observed so that more accurate control of the ~L

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This qeneral need has been recognized, and we are aware of two systems which have been proposed particularlY for use in monitorinq characteristics associated with a cementing job at a well site. The PACR system~of Dowell Schlumberger monitors pressure, flow rate and density and provides a qraphic display and maqnetic tape recordinq. In this sys-tem, each sensor for detecting the respective characteris-tics requires individual cablinq to be run directly to the central recording unit. Furthermore, this system is limited to monitorinq three density, three pressure and six flow rate characteristics. Additional characteristics can be monitored, but this requires a complete duplicate PACR
~ystem. Another system, the PDR system of Halliburton Company (the assi~nee of the present invention) has limita-tions similar to the PACR system.
Althouqh the PACR and PDR systems provide automated monitorinq of a number of characteristics associated with a process, they have relatively limited capacities before entire duplicate systems need to be used. Furthermore, if ~uch duplicate systems are used, then there is no one cen-tral recordinq station compilinq all the monitored informa-tion.
Another shortcoming of the PACR and PDR systems is that they require individual conductors from each transducer or detector to be run to the central recordinq unit. This is relatively expensive in that such runs of cablinq can be ,: ~
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lonq. Such multiple conductors require additional mainte-nance and can create hazardous situations to personnel when they are strung throuqhout the well site.
~ further limitation is that the P~CR and PDR systems are not readily adaptable for accommodatinq dispersed loca-tions where conditions or characteristics are to be moni-tored as well as where equipment is to be subsequently con-trolled to chanqe the conditions or characteristics. That is, these systems are primarily, if not exclusively, uni-tized data acquisition systems to which multiple cables are run for conveying the monitored signals. They do not in-clude modulari~ed components which can be dispersed through-out a process area for both monitoring conditions and con-trollinq the process.
Therefore, there is the need for an apparatus and an associated method which can be used at dispersed locations throuqhout a process area for retrievinq data to be used in monitorinq the process and for applyinq control siqnals, such as to chanqe the monitored conditions or charac-teristics.

S~mma~Y-of--t-he Invention The present invention overcomes the above-noted and other shortcominqs of the prior art by providinq a novel and improved data acquisition apparatus and method. Both the apparatus and method are adapted for use at locations throughout a process area for retrieving data to be used in 3~ 3 monitorinq the process and for applying controls to the pro-cess e~uipment to chanqe the conditions or characteristics.
sroadly, the data acquisition apparatus o~ the present invention comprises input means for receivinq electrical siqnals from at least one transducer; diqital storaqe means for storinq diqital siqnals corresPonding to the electrical siqnals received by the input means; first microcomputer means, connected to the input means and the diqital storaqe means, for transferring the diqital siqnals into the diqital storage means; and second microcomputer means, connected to the digital storaqe means, for transferrinq the diqital siqnals out of the diqital storaqe means onto a transmission line.
The method of the present invention comprises repre~
senting a detected characteristic as a digital electrical siqnal generated at a location near where the detected characteristic exists; operatinq a first microcomputer at the location to transfer the diqital electrical siqnal into a diqital memory; and operating a second microcomputer at the location to transfer the diqital electrical signal from the diqital memory to a port connectible to a communication conduit extendinq away from the location. This method further comprises operatinq the second microcomputer to tr~nsfer digital control data from the communication conduit to the diqital memory; and operatinq the first microcomputer to receive the diqital control data from the diqital memory and to provide a control output siqnal in response to the .

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digital control data for changing the characteristic which has been detected.
Therefore, from the foreqoing, it is a qeneral object of the present invention to provide a novel and improved data ac~uisition apparatus and method. Other and further ob~ects, features and advantages of the present invention will be readily apparent to those skilled in the art when the followinq description of the preferred embodiment is read in conjunction with the accompanyinq drawinqs.

Brief Descrl~tion of thQ Drawings FIG. 1 is an illustration of a data acquisition system constructed in accordance with the preferred embodiment of the present invention.
FIGS. 2A-~B are a representative block dlaqram of the system of the preferred embodiment of the present inven-tion.
FIG. 3 is a plan view of a display unit of the system o~
the preferred embodiment of the present invention.
FIG. 4 is an end view of the display unit.
FIG. 5 is a sectional elevational view of one of the data acquisition modules contained within the display unit as taken alonq line 5-5 in FIG. 3.
FIGS. 6A-6B are a schematic circuit diaqram of the cir-cuit contained on a display board of the data acquisition module sho~n in FIG. 5.
FIGS. 7A-7B are a schematic circuit dia~ram of the cir-,, ' , ..,., " ....",. ..

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r cuit contained on a microprocessor circuit board of the dataacquisition module shown in FIG. 5.
FIGS. 8A-8C are a schematic circuit diaqram of the cir-cuit contained on an input/output/power board of the data acquisition module shown in FIG. 5.
FIGS. ~A-9B are a schematic circuit diagram of the cir-cuit contained on a random access memory/battery backup board of the data acquisition module shown in FIG. 5.
FIGS. 10~-lOB are a schematic circuit diaqram of the circuit contained on a local area network board of the data acquisition module shown in FIG. 5.
FIG. 11 is a plan view of a recorder unit of the system of the preferred embodiment of the present invention.
FIG. 12 is an end view of the recorder unit.
FIG. 13 is a plan view of the recorder unit with the key~oard panel removed.
FIG. 14 is a schematic sectional view of the recorder unit taken along line 14-14 in FIG. 13.
FIG. 15 is a flow chart of a proqram for controllinq a control microcomputer in the data acquisition module.
FIG. 16 is a flow chart of a proqram for controllinq a transmission mlcrocomputer of the data acquisition module.
FIG. 17 is a flow chart of a program for controlling a microcomputer in the recorder unit.

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~ ,'"' ' ` '' ' ';'"` ~; .',. ~ ' ' , ` ', ' ,,;' . '' '. ' Detailed Description of the Preferred Embodiment The data transfer system constructed in accordance with the preferred embodiment of the present invention includes interface means for communicatinq with an operation, such as an oil or qas well cementinq operation which is to be con-trolled in response to the data transferred throuqh the pre-ssnt invention. Associated with such an operation are different detectable conditions or characteristics. In FIG.
1, the interface means is particularly embodied as a display unit 2, adapted for beinq located near where a plurality of detectable characteristics are to be monitored, for receiv-inq electrical inputs representing magnitudes of detected ones of the characteristics and for diqitally encoding the electrical inputs. ~hese inputs in the preferred embodiment are received from suitable transducers which convert the characteristics, such as pressure, flow rate and density, into the correspondinq electrical siqnals representinq the maqnitudes or values of the characterlstics. In FIG. 1, two pressure transducers 4, 6, two flow rate transducers 8, 10 and a density transducer 12 are illustrated as beinq con-nected by suitable electrical conductors to the display means 2. In the preferred embodiment particularlY adapted for use in monitorin~ conditions of a cementinq ~ob at an oil or gas well site, the pressure transducer is of a type as known to the art, as are the other transducers, such as ~lowmeter or tachometer transducers and diqital or U-tube densometers. These transducers or, more generally, these :~ .
',~, .' detectors have predetermined or predeterminable response characteristics which can be used for calibratinq purposes as subsequently described.
The system of the present invention also includes a central processinq means for receivinq information from, and ror sendinq information to, the interface means. In FIG. 1 the cPntral processinq means is shown embodied as a record-inq unit 14, adapted for beinq located at a distance from the display unit 2, for recordinq the diqital encodinqs of the electrical inputs received at the display unit 2.
The data transfer system also broadly includes local area network means for connecting the interface means and the central processinq mean~ so that the information re-ceived from. and the information sent to, the interface means is transferred only throuqh a sinqle information transfer conduit. This is distinguishable from the PACR and the PDR systems described hereinabove which reguire indivi-dual conduits or conductors from their transducers to their central recordinq unit. In the FIG. 1 embodiment of the present invention, the local area network means particularly includes a single electrical cable 16 connected between the display unit 2 and the recording unit 14. In the preferred embodiment the cable 16 includes two pairs of electrical conductors. One pair of electrical conductors is dedicated to transferring the diqital encodinqs of the electrical in-puts; the other pair is dedicated to indicatinq the instants in time durinq which the diqital encodinqs beinq transferred :, ,: , ; ' ,~ ' "

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on the one pair are valid. In the broadest aspects of the present invention, this other pair is not needed ~or pro-vidinq a conduit through which the digital data representinq the monitored conditions can be transferred, if the validitY
of the diqital encodinqs is inherent in the manner of en-codinq or other~ise assured. The local area network means also includes connectinq circuitry within the display unit 2 and the recordinq unit 14 as will be more particularlY
described hereinbelow.
The structure and methodoloqy of the displaY unit 2, the recordinq unit 14 and the local area network interconnect circuit will be more particularly described hereinbelow with reference to the remaining drawinqs. It is to be noted, however. that the followinq hardware and software descrip-tions are not to be taken as limitinq the scope of the pre-sent invention because it is contemplated that other types of hardw~re and software can be utilized in practicing the invention.

Display Unit 2 The external appearance of the preferred embodiment of the display unit 2 is shown in FIGS. 3 and 4. The display unit 2 includes a portable housinq 18 havinq a body 20 in which the electrical components of the display unit 2 are contained. The housinq 18 also has a removable lid 22 and a plurality of mechanical connectors 24 to which cables are connected for providinq electrical continuity into and out ' 9~3 of the housinq 18. As shown in FIG. 4, the connectors 24 include two pressure transducer connectors 26, 28, two flow rate transducer connectors 30~ 32 and one density transducer connector 34. The connectors 24 also include a connector 36 to which the cable 16 is connected and a power-in connector 38 to which an external power cable 39 (FIG. 1~ is connected ~OL^ transferrinq power from an external power suply to the dis~lay unit 2. A power-out connector 40 is also mounted in the side of the body 20 of the housing 18 so that a power cable 41 can be connected to provide power to an external device. such as another display similar to the display means 2 or. as illustrated in FIG. 1, to the recordinq unit 14.
Althouqh FIG. 1 shows the display unit 2 and the recordinq unit 14 sharinq power from the external power supply via the cable 41, it is contemplated that this will be done only when the two units are relatively close toqether. When the units 2. 14 are in the field and spaced across a well site ~rom each other, the more likely confiquration will be for each to have its own local external power supply (e.q., a truck battery) connected thereto. This confiquration re-duces the "lonq-distance" cablinq to just the sinqle data transmission cable 16, thereby maximizinq the reduced cabling advantage of the present invention over the PACR and PDR systems.
Although not shown in the drawinqs, another connector is contemplated to be included on the housinq 18. This connec-tor will p~rmit different display units to be locally inter-. .
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~l%~ 3 connected in a manner which permits each display unit accessto the sinqle data transmission cable 16 which runs from only one of the display units to the sinqle recordinq unit 14. That is, in the system of the present invention, a plurality of display units 2 can be interconnected in a ~aisy chain manner whereby only a sinqle cable 16 needs to be run from one of the display units to the recordinq unit 14. When additional display units 2 are used, the monitored data from the other units are transferred onto the cable 16 throu~h branch information transfer conduits or cables simi-lar to but shorter than the cable 16. These branch cables are physically connected between two of the display units 2, but ultimately in communication with the sinqle information transfer conduit 16 extendinq to the recording unit 14.
Each such branch information transfer conduit has a lenqth which, in the preferred embodiment, is substantially shorter chan the lenqth of the sinqle information transfer conduit 16 so that aIl the disp].ay units remain within substantially the same environment of the monitored process. That is, all of the display units are relatively closely located since they are used to detect different characteristics associated with the overall operatlon they are monitorinq. Thus, all the display units are located within the environment of the monitored operation; however, the single recordinq unit 14 used with all of the display units is remotely located out-side of the immediate environment or vicinity of the opera-tion so that the recordinq means 14 need not be constructed .. :
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to withstand whatever adverse conditions might exist within the environment of the monitored operation. In the pre-ferred embodiment, the overall system is expandible to accommodate thirty-two inputs on the sinqle pair of data transmission conductors in the cable 16.
Contained within the housinq 18 of each display unit 2 are three data acquisition modules 43. In the preferred embodiment these data acquisition modules define pressure data acquisition means for receiving and encodinq at least one pressure siqnal, flow rate data acquisition means for receiving and encodinq at least one flow rate siqnal, and density data acquisition means for receivinq and encodinq at least one density siqnal. Each of these data acquisition modules is connected to the sinqle pair of electrical con-ductors defininq the monitored data transferral conduit con-tained within the cable 16.

Data Acquisition Module 43 Althouqh each data acquisltion module miqht be adapted to receive and encode a different type of characteristic ~e.q., pressure, flow rate or density), each module is a similarly constructed apparatus havinq the components qen-erally identi~ied in FIG. 2A. Broadly, each data acquisition module comprises input means for receivinq electrical siq-nals from at least one transducer (it should be noted, how-ever, that a data acquisition module has uses other than acquirinq data so that it is operational even without beinq ,' :

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connected to anY transducers; for example, a module could simply provide a clock or an alarm clock function or it could perform mathematical operations on data inputs based on internally stored tables of information). Each module further comprises diqital storaqe means for storing digital siqnals correspondinq to the electrical signals received by the input means; control microcomputer means, connected to the input means and the diqital storaqe means, for trans-ferrinq the diqital siqnals into the diqital storaqe means;
and transmission microcomputer means, connected to the digi-tal storage means, for transferrinq the diqital si~nals out of the diqital storaqe means onto a transmission line. The diqital storaqe means defines connector means for connectinq the control microcomputer means, which performs direct com-munications with the oil or qas well operation in the pre-rerred embodiment, and the transmission microcomputer means, which passes the information to the recordinq unit 14.
~ s shown in FIG. 2A, the input means includes two con-nectors for connectinq to two transducers. For the pressure data acquisition module of the display means 2, these two connectors are the connectors 26, 28, whereas for the flow rate data acquisition module, these two connectors are the connectors 30, 32. In the preferred embodiment, FIG. 4 shows that only one connector (iOe., connector 34) is asso-ciated with the density data acquisition module; however, the density data acquisition module has the qeneral con-fiquration shown in FIG~ 2A.

3~3 The input means of each data acquisition module 43 also includes digitizing means for connectinq the two connector means with the control microcomputer. In FIG. 2A, the pre-ferred embodiment of the diqitizinq means is shown as beinq adapted for receivinq two different types of transducer out-puts. One is a voltaqe or current output and the other is a frequency output. To accommodate the voltaqe or current output. the diqitizinq means includes a voltaqe to frequency converter 42 which converts the respective transducer siqnal into an electrical siqnal having a frequency. To accom-modate the frequency transducer output, the diqitizinq means includes an amplify and square means 44 for providinq another electrical siqnal havinq a frequency in response to the applied frequency siqnal from the respective frequency transducer. Also included within the digitizinq means is a counter means 46 for providinq a diqital siqnal to the control microcomputer in response to the frequency of one of the two electrical siqnals provided by the voltaqe to fre-quency converter 42 and the amp and square circuit 44. To selectably connect one of these two siqnals to the counter means 46, the diqitizinq means further includes switch means 4B.
The diqital storaqe means of each data acquisition module 43 constructed in accordance with the preferred embo-diment of the present invention includes a dual port random access memory 50 havinq a first port connected to the con-trol microcomputer and havinq a second port connected to the ..
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'., ," ' transmission microcomputer. The random access memory 50 provides commonly accessible storaqe locations in which information is stored by one of the two microcomputers and -retrieved by the other of the two microcomputers. Such other one of the microcomputers is actuated to retrieve the information by monitorinq a respective status word contained in a ~redetermined storaqe location within the random access memory 50. In the preferred embodiment there is a status word storaqe location in which the control microcomputer writes to actuate the transmission microcomputer to perform a function on the memory, and there is a second status word storaqe location different from the first one, in which the transmission microcomputer writes a second status word to actuate the control microcomputer to perform a function on the random access memory 50.
The control microcomputer is shown in FIG. 2A as in-cludinq a microprocessor 52 connected to the counter 46 and the random access memory 50. The microprocessor 52 is also connected to proqram storaqe means 54 for retaininq a pro-qram to operate the microprocessor 52, ana the micropro-cessor 52 is connected to a random access memory 56 havinq a capacity for storinq up to several hours of monitored data (of course. such capacity need not alwaYs be fully used because transfers over the cable 16 to the recordinq unit 14 for storaqe in the memory there can be made).
Associated with the control microcomputer, and forminq another part of the data acquisition module 43, is a serial ~.~.f3~7923 transmitter and receiver means 58 for transmittinq external information from and receiving external information for the microprocessor 52 separately from that information trans-ferred via the random access memory 50. A parallel input/
output means 60 for providinq local information transfer to and from the microprocessor 52 is also included in the module 43. Throuqh the I/O circuit 60, analog switches 62 ~nd a display 64 are controlled and inputs from a keyboard 66 are received. Also connected to the microprocessor 52 are diqital to analoq conversion means 68 for providinq ana-loq control siqnals to one or more external devices in response to the monitor microcomputer. Each module 43 is also designed for havinq internal power supplY capabilities as indicated by the power supplies 69 included in FIG. 2A.
The transmission microcomputer is shown in FIG. 2A as includinq a microprocessor 70 connected to the random access mamory 50; proqram storaqe means 72. connected to the micro-processor 70, for retaininq a proqram to operate the micro-processor 70; random access memory 74 connected to the microprocessor 70; and serial input/output means 76 also connected to the microprocessor 70. The serial input/output means 76 communicates the diqital siqnals from the diqital storaqe means defined by the random access memory 50 to the common pair of conductors in the cable 16. Time data is also communicated throuqh the serial input/output means to another common pair of conductors of the transmission line.
This is indicated by the LAN (local area networ]~) block in ; ., .
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79~3 FIG. 2A.
These elements of each data acquisition module 43 are mounted in a housinq 78 (FIG. 5) havinq a receptacle member 80 and a detachable cover member 82 in which two disPlaY
openinqs 84, 86 are defined and to which the keyboard 66 is retained. Vertically arrayed within the receptacle member 80 are a plurality of printed circuit boards on which the circuits defininq the aforementioned elements of the data acquisition module 43 are mounted. These boards include:
(1) a display board 88 havinq display circuit means mounted thereon for providinq a visual output observable throuqh the two display openinqs 84, 86; ~2) a control microcomputer board 90 havinq the microprocessor 52 and related circuitrY
mounted thereon for receivinq inputs from the keyboard 66 and for controllinq the display circuit on the board 88; (3) an input/output/power board 92 havinq the various aforemen-tioned input and output circuits mounted thereon as well as havinq power input circuit means mounted thereon for pro-vidinq suitable electrical voltaqe to the data acquisition module in r~sponse to the external power source; (4) a local area network board 94 havinq the random access memory 50 and the microprocessor 70 and its related circuitry mounted thereon; and ~5) a random access memory board 96 havinq the random access memory ban~ 56 mounted thereon for storinq data received from the microprocessor 52 and havinq internal power supply circuit means for enerqizinq the random access memory 56 when the power input circuit on the board 92 is not providinq electrical energy to the data acquisition module 43. A termination board 98 is also included with the enclosure defined by the housinq 78. Each of the boards 88-96 and their related circuits will be more particularlY
described with reference to FIGS. 6-10, in which drawinqs the circuits defininq the elements shown in FIG. 2A are identified by the same reference numerals used in FIG. 2A.
These boards will be further described as follows; however, a more detailed description of these circuits and their operation will not be qiven because they are apparent from the drawinqs.

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Display Board 88 The circuit for the display board 88 is shown in FIGS.
6A-6B. The circuit includes two 6-diqit liquid crystal displays 100, 102 visible throuqh the display openinqs 84, 86. The board operates by decodinq with a decoder 104 the upper four bits of an 8-bit byte. The lower four bits of the byte are the bcd diqits to be displayed. Three decimal points can be driven by the decoder. The addresses are:
0----Upper Display, First Diqit (Leftmost) l----Upper Display, Second Diqit 2----Upper Display, Third Diqit 3----Upper Display, Fourth Diqit 4----Upper Display, Fifth Diqit 5----Upper Display, Sixth Diqit (Riqhtmost) 6----Lower Display, First Diqit (Leftmost) , . ' ' , ', ' :.

- ~1.. 2~ 3 7----Lower Display, Second Digit 8----Lower Display, Third Diqit 9----Lower Display, Fourth Diqit 10---Lower Dlsplay, Fifth Dlqit ll---Lower Display, Sixth Diqit (Riqhtmost) 12---Lower Display Decimal Point 13---Upper Display Decimal Point 14---Unused 15---Unused The diqits displayed are: 0='0' 8='8' 1='1' 9='9' 2-'2' 10='L' 3='3' ll='H' 4='4' 12='P' 5='5' 13='A' 6~'6' 14='-' 7='7' 15=BLANK
This board is driven by the microprocessor 52 throuqh the I/O port 60. The board requires +5 VDC for operation.

Microcomputer Board 90 The control microcomputer board 90 is shown in FIGS.
7A-7B; its major components are an 80C85 CPU (the micropro-cessor 52), an 81C55 RAM/IO/Timer (the I/O means 60), an 82C53 triple counter (the counter means 46), a 27C256 EPROM
(the proqram storage means 54~, an 82C51 UART (part of the serial transmitter and receiver means 58), and two AD558 ' ' .; ' . , ,.. : ,,:
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~iqht-bit D~C's (tbe diqital to analoq converter means 68):
` - 80C85 - CMOS version of the Intel~8085. Address ran~e ., is 65536 bytes. Word lenqth is eight bits.
Interrupts are RST7.5 and RST5O5 (used as the interrupt for a debuqqinq proqram). All other interrupts are disabled. The crYstal requency i5 3579545 Hz. The CPU clock fre-quency is ~ tbe crystal frequency. RST7.5 `
should occur ten times per second. RST5.5 should be always low.
81C55 - CMOS version of the Intel 8155. It has two eiqht-bit ports, a 6-bit port, and a 14-bit timer. The timer divides the CPU clock down that is used by the 82C51 in determininq a baud rate. The ports are divided into two eiqht-bit ports and one six-bit port as follows: Port A=8 bits Port B=8 bits Port C=6 bits Port A is used for controllinq the display 64, and the upper half of Port B and the lower four bits of Port C get a key value from the ;~
keyboar~ 66 by a scanninq of the rows and columns. The rest of Ports B and C are used for control functions on the input/output/
power board 92 and tbe memory board 96. The lower four bits of Port B are latcbed by the . . : .

79~3 two upper bits of Port C on the input/output/
power board 92. Only bit 4 of Port C is used for latchinq and it only latches bits l and 0 of Port B. The Port Addresses are:
Control=70~ (160 OCTAL) Port A=71H (161) Port B=72H ~162) Port C=73H tl63) TIMERLO=74H ~164) TIMERHI=75H t165) 82C53 - CMOS version of the Intel 8253. This is a triple sixteen~bit counter. Counter 0 is used to qenerate the RST7. 5 interrupts. The input to the Counter 0 is a frequency derived from a 4020 ripple counter runninq of the CPU clock.
This 4020 also qenerates 60Hz for the display board 88 backplane. The frequency goinq into the Counter 0 is the CPU clock divided by 32.
Counter 2 is connected to the output of the density amp and square on the input/output/
power board 92 or the VFC100 or reqular amp and square (selectable throuqh the 4052 analoq switch 48 in FIG. 8A). Counter 1 is connected to the voltaqe to frequency converter for channel 1 or the amp and square (selectable throuqh the 4052 analoq switch 48 in FIG. 8A).
Counter 1 was desiqned to work with the . .
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v~ltaqe to frequency converters to measure pressure on a 4-20m~ siqnal. While this chip has three sixteen-bit counters and one control reqistPr, it only takes up four port addresses. They are:
Control Req=63 hex (143 octal) Counter 2=62 hex (142 octal) Counter 1=61 hex (140 octal) Counter 0=60 hex (140 octal) Readinq twice from the counter address obtains a sixteen--bit counter result.
27C256 - CMOS 32768 X eiqht-bit EPROM. This EPROM
occupies Memory Reqion 0-7FFF hex (77777 octal). It has interrupt jump instructions, the debuq proqram, and a lookup table for the keyboard alonq with the main PASC~L operatinq proqram.
82C51 - CMOS version of the Intel 8251. This chip is a proqrammable communication interface. It is used for serial communications to external devices. The input/output lines (3, 17, 19, 23) are buffered on the input/output/power -` board. The port~address for the 82C51:
Control Status Reqister = 51 hex tl21 octal) Data Reqister = 50 hex (120 octal) AD558 - These eiqht-bit DAC's provide a 0-2.55 volt output that i3 controlled by an eiqht-bit word -.
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from the CPU. The port addresses are:
Channel 1=40 hex (100 octal) Channel 2=30 hex (60 octal) Three other chips are on this board alonq with several connectors. The 74HC138 chip 106 is a CMOS decoder similar to the 74LS138. It de-codes the CPU port address space into eight blocks: the first three blocks are unused;
the fourth is used by the channel 2, eiqht-bit DAC; the fifth block is for the channel 1, eiqht-bit DAC; the sixth is for the 82C51; the seventh is used for the 82C53; and the eighth block is used for the 82C55. The 74HC373 chip 107 is used for latchinq the lower eiqht bits or address. This is a requirement from the 80C85 bus structure. The 4020 chip 108 is used to divide the system clock for interrupt timer and LCD backplane.

:
Input/Output/Power Board 92 The input/output/power board 92 shown in FIGS. 8A-8C has the functions required for conditioninq of a) external power, (b) 4-20mA siqnals, c) low level, low frequency pulses, d) high level high, frequency pulses, e) RS-422 buf-ferinq, and f) analoq output switchinq. It provides the path for siqnals to move into or out of the housinq 78 of the module 43. The VFC100 (the voltaqe to frequency con-. .
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verter 42 -- FIG. 8A) is for the 4-20mA conversion. The LM211's and LM219 (the amplify and square means 44 -- FIG.
8C) are for the frequency conditioninq. The JBl, JB2, JB3 jumpers on the board select between a flowmeter siqnal or a digital p/m tube from the densometer. The 7805 device 110 (FIG. 8A) takes the raw batterY voltaqe obtained throuqh the connector 38 down to a requlated five volts. The DC-DC con-verter 112 chanqes the voltaqe to + and -15 volts. The power cube 114 chanqes the voltaqe to about 90 VAC. This is used to backlight the displays 100, 102. The DS1691 chip 116 (part of the serial transmitter and receiver means 58) buffers the RS-423 or RS-422 output. The 78C120 chip 118 (another part of the means 58) receives serial siqnals from external devices. Jumper JB4 .selects RS-423 or RS-422 transmission. The 74HC75 chips 120. 122 are latches that are used to turn the analoq switches 52 on and off.

Random Acess Memory Board 96 The random access memory board 96 has eiqht 8R x 8-bit CMOS ~tatic RAM chips 124 as shown in FIGS. 9A-9B. The decodinq of the chips 124 is done by a 74HC138 chip 126.
Tne switches 127 on the board make it possible to be bank selected by the 81C55 on the CPU board 90. For battery backup to retain the contents of the chips 124 in the event of a primary power outaqe, the batterY jumper should be in place and the LM393 dual comparators 128a, 128b should be in place.

.. ~.. : ,' .
. . .
: ~,: .: . . .

: -.. '. :

37~

Local Area Network Board 94 The circuit of the this microprocessor-based local area network board 94 shown in FIGS. lo~-lOs runs a proqram stored in an EPROM (the proqram storaqe means 72). This proqram transfers information from a dual port RAM (the ran-dom access memory 50) out RS-485 line drivers to the cable 16, and it receives data from the RS-485 line of the cable 16 and places it in the dual port RAM. The principal com-ponents of this board include: -7130 - (dual port RAM 50) lK of static RAM which can be accessed by both microprocessors 52, 70.
It is decoded at location F800-FBFF in the data acquisition module 43 and E800-EBFF in the recordinq unit 14.
Z80 - (microprocessor 70) A CMOS 8-bit micropro-cessor which does all calculations and exe-cutes instructions to satisfy a part of SDLC
LAN protocol to transmit data over an RS-485 balanced line (the twisted pair of conductors in the cable 16).
27C256 - (proqram storaqe means 72) 32K EPROM for software storaqe.
SIO - (chip 129. part of serial input/output means 76) Chanqes data from serial to parallel and vice versa and implements part of the hardware requirements for the SDLC protocol.
6264 - (random access memory 74) 8K CMOS RAM at . ~ :. :, 7~3~3 memory location 8000-9FFF for microprocessor stack, scratch pad, etc.
DS3695 - (devices 130, 131 part of serial input/output -means 76) Data and clock conditioners to meet RS-485 hardware requirements for hiqh speed serial transmission over a balanced line.

Terminator Board 98 The receptacle member 80 of the housinq 78 has a per-manently connected printed circuit board (the terminator board 98) that connects the outside world with the internal circuitry of t~e data acquisition module 43 bY pins ultraso-nically welded throuqh the ~ack of the shell. These pins are then soldered to the terminator board 98. A 34-pin rib-bon cable carries the signals up to the otber boards in the module 43.

.
Althouqh the data acquisition module 43 forms an inte-qral part of the overall data acquisition system described herein, the module 43 can be used in a stand-alone data acquisition mode. For example. the module 43 can be con-nected to a transducer and a power~supply and allowed to collect data and retain the data in its internal memory.
This same module can be used from job to job to collect and internally store data from the various jobs ~makinq sure that the maximum internal storaqe caPaCitY is not exceeded so that data from the earlier jobs are not overwritten and ., ' ';, ,;
`. ' ~ "',''' ~, ' '7~

lost). At some suitable future time, this module can be connected to a suitable device, such as the recordinq unit 14, for transferrinq the data which have been collected and stored in the module.
The data acquisition module 43 can also be used as a controller for outputtinq control siqnals to control the monitored process, for example. With respect to the illus-trated praferred embodiment, control siqnals can be provided ~hrouqh the analoq switches 62 or the diqital to analoq con-verters 68, for example.

Recordinq Unit 14 The recordin~ unit 14 is shown in FIG. 2B as includinq a local area network board 132 constructed similarly to the board 94 in the data acquisition module 43 of the display unit 2. The circuit 132 couples with the local area network cable 16. The recordinq unit 14 also includes a sinqle board microcomputer system 134 utilizinq two floppy disk drives. FIG. 2B shows that the microcomputer system 134 includes a Z~0 microprocessor 13~. a 4K EPROM 138 for pro-qram storaqe, and a dual floppy disk controller and drive means 140 for receivinq a maqnetic storaqe disk (particularly. a miniature floppy diskette in the preferred embodiment) on which at least part of the information received from the display unit 2 is to be stored. The microcomputer system 134 also includes a monitor interface circuit includinq another EPROM 142, a video random access - . ` - '; ' : . , ` :
~ ".

memory 144, and a CRT controller 146. A parallel `input/output circuit 148 communicates with a keyboard 150 and a printer 152. A serial input/output circuit 151 provi-des a communication path to external devices, such as a remote computer. A 128K random access memorY 153, havinq a memory management chip (MMC), is also included in the recordinq uni~ 14. These elements are of types as known to t~e art. Particularly, the sinqle board microcomputer system 134 of the preferred embodiment is the Model MSC-ICO
sinqle board computer from Mountain Side Computer.
The aforementioned elements of the recordinq unit 14 are contained in a portable housinq 154 as shown in FIGS. 11-14 (it i3 to be noted that in other specific implementations of the recordinq unit 14, the components can be positioned dif-ferently in the housinq 154, such as by movinq the keyboard 150 and the printer 152 to the left side and movinq the disk drive to the riqht side, which left and riqht sides are as the housinq 154 is oriented in FIG. 11, for example). The housinq 154 is a suitable carryinq case includinq a body 156, a removable lid 158 and two connectors 160, 162. The connector 160 couples with the local area network cable 16, and the connector 162 couples with the power cable 40, which as previously described runs to the display unit 2 or to a closer external power suppIy. The disk drives of the means 140, the keyboard 150 and the printer 152 of the recordinq unit 14 are mounted in the housinq 154 as indicated by their identifyinq reference numerals shown in FIGS. 11, 13 and 14.

. . .
~ . : , .~. . ....
:' :

''3~3 The circuit boards containinq the LAN connections and the sinqle board computer are moun~ed below the illustrated com-ponents as indicated in FIGS. 13 and 14.
The floppy disk drive is used in the preferred embodi-ment to record data evsry one second with respect to each data ac~uisition module 43 so that a complete history is obtained. A total of seven hours of storaqe can be placed on one of the floppy disks used in the preferred embodiment~
In this preEerred embodiment, the floppy disk drive is a Sony~Model MP-F53W drive.
The printer 150 is an Epson*HS-80 printer controlled for creatinq strip chart-like printouts. The keyboard 152 is an Advanced Input Devices Model MK-059 alphanumeric encoded keyboard.

Local Area Network Cable 16 The local area network means has been previously described as beinq embodied in the preferred embodiment as a sinqle data transer cable 16 includinq a sinqle pair of wires ~identified in FIGS. 2A-2B by the reference numeral 164) over which the monitored data are transferred. In the preferred embodiment the lenqth of the cable 16 is uP to 2.000 feet. More qenerally, the cable provides a sinqle information transfer conduit which has a suitable len~th sufficient to allow the recordinq unit 14 to be located bsyond the immediate environment of the oil or qas well operation (or other operation) when the displaY unit 2 is .

:i .

, . . . .... .
;:... : ..

located within such immediate environment so that the abi-lity of the recording unit 14 to operate is not adverselY
affected by the operation. O~ly this one lonq data transmission cable is required in the present invention because all other cablinq is throuqh shorter branch cables connected from one display unit to another in a daisy chain confiquration. This reduces cablinq costs and maintenance requirements as well as reducinq cablinq conqestion across the area in which the present invention is used.
Althouqh only a sinqle pair of wires is needed to trans-fer the monitored data in the broadest aspects of the data transfer system, in the preferred embodiment the cable 16 includes a second pair of conductors ~identified bY the reEerence numeral 166 in FIGS. 2A-2B) for transferrinq timinq siqnals between the display unit 2 and the recordinq unit 14. These timinq siqnals are used to synchronize the hiqh speed data transfer occurrinq on the conductor pair 164.
~ lthouqh the preferred embodiment is specifically described as includinq "wires," which miqht imply a metallic composition. it is also contemplated that the transfer or conductor medium can be any suitable means, which miqht be of a material other than metallic wires, such as a fiber optic transmission medium.

, , ~: ' : .

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~l.%~7~

Sotware The software by which the two microcomputers in each of the data acquisition modules 43 of the display unit 2 and the microcomputer in the recordinq unit 14 operate can be of any suitable type; however, the preferred embodiment of such software is depicted by the flow charts in FIGS. 15-17 and as is otherwise described throuqhout the textual specification.
The flow chart of FIG. 15 describes the control proqram for the microprocessor 52; the flow chart of FIG. 16 describes the control proqram for the microprocessor 70; the flow c~art oE FIG. 17 describes the control proqram for the microprocessor 136. Broadly, the proqram for the micropro-cessor 52 causes it to operate so that the data from each transducer monitored thereby is qathered six times per second. The proqram of FIG. 16 controls the microprocessor 70 so that it continually loops until the RAM 50 status word it is monitorinq is chanqed by the microprocessor 52.
thereby causinq the microprocessor 70 to obtain the data from the random access memory 50 and store it in the random access memory 74 until a command is received from the microprocessor 136 of the recordinq unit 14. The control proqram for the microprocessor 136 operates so th~t data are retrieved from the display unit 2 and concurrentlY displayed throuqh the printer 152 and stored on a floppy disk in the controller and drive means 140. The confiqurations of the memories in which these proqrams are stored and throuqh which memories these proqrams operate are specifically .. . .
:~, ,, ".
. .
: .
.. . .
: , :. .

.. ....
. .

9~3 represented by the memory and input/output maps shown alonq the riqht-hand edqe of FIGS. 2A-2B.
In a specific embodiment, the software for the displaY
unit 2 implements a portion of the known SDLC protocol usin~
the followinq parameters:
1) The dual port RAM 50 interfacinq between the z80 microprocessor 70 and the data collection system under control of the microprocessor 52 is memory ~ mapped at F800-FBFF hex.

2) A data transmission is confiqured with the followinq header:

UNIT USE DATA O~D D~TA E~
ADDRESS _LATER LENGTH__ _ID ID CODE
F800 Eyte Byte Byte Byte Byte¦ Eyte Data (lenqth in byte 2) _ 0C~ _ __1_ 02 _ __03_ 04 1 05 Ranqe C -lF
and FF

The same header precedes all data transmission. Data lenqth i3 currentlY limited to 79 hex b~tes unless a "block transfer" mode is used.
Data from F800 in the R~M 56 is moved to F880 in the RAM
50 with the correct address.
"Command ID" is a code to pass commands between units.
"Data ID" tells how to decode the data block.

Handshakinq between the Z80 LAN board 94 and the control microcomputer board 90 is done in memory locations F900 and F980. On initialization the microprocessor 52 writes an AAh ',.. ' ' ;, :

- , 9~3 to F900 in the RAM 50. The microprocessor 70 writes an AAh back to F980h. Then to check for errors, the microprocessor 52 writes 55h to F900h and the microprocessor 70 echos it back to F980h.
Once the microprocessor 52 sets up the data block at F800h it increments F900h and the microprocessor 70 retrieves the data block into its RAM 74 and awaits a com-mand from the recordinq unit 14. After the transmission to the recorder unit 14 occurs, the microprocessor 70 incre-ments F980h in the RAM 50 and the microprocessor 50 can look to F980h for the reply.
In the recordinq unit 14 the EPROM 138 is used to qet the sinqle board computer of 134 started. The actual operatinq proqram for the computer 134 is, however, stored ~n a 3.5" floppy diskette loaded in the floppy disk con-troller and drive means 140. The actual CP/M3 operatinq system, whicb is a known system used in the preferred em~o-diment of the present invention, takes over when the boot from the EPROM loads the first sector of Track 0 on Disk Drive A. This is CPM. LDR ~ This loader continues to load the rest of Track 0. This in turn loads a file from the disk called CPM3.SYS which contains the Basic Disk Operatinq System (BDOS) and the Basic Input Output System (BIOS). The last thinq BIOS does is load a file called CPP.COM. The Console Command Processor (CCP) looks for a file on the disk called PROFILE.SUB. It uses SUBMIT.COM to execute the PROFILE.SUB commands, which leads to the major operatinq .
:"; ,:.. ,,. , , :
. .
,, . , . . ,, . :, ......
-~. ... ,. - , . . .

f~

proqram.
Other files used in a specific implementation and known or readily ascertainable to those in the art for performinq the indicated functions with the specific hardwars identi-fied herein are:
LANM~RC.COM - Main data acquisition and storaqe control SYSFMT.COM - HALDOS 320K disk format MDFMTI.COM - HALDOS 720X disk format INIT.COM - Systems initialization CONR.COM - Confiqure strip chart to determine which characteristics are charted PLABAK.COM - Strip chart playback PLABAKI.COM - Tabular chart playback DLTPB.COM - Data acquisition module dump tabular Playback DOWNLOAD.COM - Read 64K RAM of data acquisition module into recordinq unit STRIP.COM - Data acquisition module dump strip chart playback RPLOT.COM - Real time printer drive (strip chart) Other files on the disk which are known and can be used by exPerienced CPiM3 proqrammers include:
LIB.COM - Create librar-y of comPiled REC files.
SID.COM - Assembly lanquaqe debuqqer.
GET.COM - Get console input from a disk file.
DATE.COM - Display and sst date and time.
GENCOM.COM - Create special CP/M3.

,.
:

.. ' ' ~ '' ~:

~379~

LINK.COM - Link REL ~iles into executable.
TYPE.COM - Display a text file on console.
PUT.COM - Send console output to disk.
~ELP.COM - Additional help for ne~- users.
DEVICE.COM - Display/ARter peripheral assiqnments.
DATESET.COM - MSC-ICO dateset proqram.
GENCP~.COM - General new CP/M System Tracks PIP.COM - Peripheral interchanqe proqram.
M~C.COM - Assembly lanquaqe-macro assembler.
SETDEF.COM - Define disk search path.
DIR.COM - Display list of file names/size/attribute.
SCR.COM - Show disk characteristics.
ED.COM - Edit a test file.
SHOW.COM - Display ASCII file to computer console.
RMAC.COM - Relocatable assembly lanquaqe assembly.
DUMP.COM - ASCII/Hex dump of disk file.
COPYSYS.COM - Create a new SYSTEM disk.
ERASE.COM - Erase a file.
SE'r.COM - Chanqe file attributes.
XREF.COM - Crossreference for MAC, RMAC.
RENAME.COM - Chanqe a file Name.
RESET.COM - Reset MSC-ICO SBC.
SAVE.COM - Save memory to disk.
IDU.COM - MSC-ICO Disk Initialize Proqram.
HEXCOM.COM - Generate COM file from Hex file.
INITDIR.COM - Set up directory for date/time.
SERIAL.COM - Chanqe baud rates on Serial Ports.

. .~ , ::
' -' ' ' . : ,,, ~:

- ~ . . ' :, :,,', .', ':

7~

FKEY.COM - Function key definition proqram.
FKEY.SYS - Store function key values.
It is contemplated that other software and networking protocols can be used in implementinq the data transfer system.

Operation Overview In the preferred embodiment the method of the present invention acquires data from a flow process at a well site.
This method, which is readily adaptable to other uses, com-prises detectinq from spatially separated locations of the flow process a plurality of characteristics (e.q., pressure, flow rate and density) occurrinq within the flow process;
convertinq, at at least one location~near the flow process, the detected characteristics into diqital electrical siqnals representinq the maqnitudes of the detected characteristics;
and transferrinq the diqital electrical siqnals over the ^
sinqle pair of transmission conductors 164 to a sinqle loca-tion remote from the flow process. The step of transferrinq includes, at each of the locations near the flow process, movinq, with the respective control microprocessor 52 at that location, the diqital electrical siqnals at that loca-tion into the respective diqital random access memory 50;
movinq, with the respective transmission microprocessor 70, the diqital electrical siqnals from the respective diqital memory 50 onto the sinqle pair of transmission conductors ' . . . ~,: " ~', , ~

~,z~

164; and receivinq, with the microprocessor 136 at the sinqle location remote from the flow process, all the diqi-tal electrical siqnals moved onto the sinqle pair of trans-mission conductors 164 from each of the one or more locations.
The foreqoinq "movinq" steps are performed within each of the data acquisition modules 43. These movinq steps are Performed by operatinq the two microcomputers contained within each respective data acquisition module 43; These operations are performed at respective locations near where the detected characteristics exist. That is. the data acquisition modules 43 (and their combination into display units 2~ are used within the environment of the monitored operation, whereas the recordinq unit 14 is used outside of thi3 environment. These operations of the two microcom-puters within each of the data acquisition modules 43 are particularly performed by modifyinq a diqital status word stored in the diqital memory 5~ linkinq the two microcom-puters when one of the microcomputers transfers the diqital electrical siqnals into the diqital memorY 50. In response to modifyinq such a diqital status word, the other microcom-putsr detects this and transfers the diqital electrical siqnal into its own independent random access memory (i.e., either the memory 56 or the memory 7~). For examPle, the microprocessor 52 writes a data word into the random access memory 50 and increments a bit of a status word also con-tained within the random access memorY 50. The micropro-. . ,:. -. ' .' , cessor 70 monitors this status word and, thus, detects when the bit has been incremented. This causes the microPro-cessor 70 to read the stored data word throuqh a second port of the random access memory 50 into its own random access memory 74. See the "Software" section above.
The method of operation of the overall system includinq both the display unit 2 and the recordinq unit 14 further comprises recordinq the transferred diqital electrical siqnals on a diqital storaqe diskette at the sinqle location which i3 remote from the operation beinq monitored.
The system of the present invention can be further oper-ated so that the recordinq unit 14 is controlled by siqnals qenerated in the display unit 2 and transferred throuqh the cable 16. This includes enterinq, throuqh the micropro-cessor 52 and from there into the random access memory 50, a control siqnal ~enerated by depressinq appropriate keys on the keyboard 66. This control siqnal is moved, by the microprocessor 70, from the random access memory 50 onto the sinqle pair of transmission conductors 164 for conductinq the monitored data throuqh the cable 16. The microprocessor 136 of the sinqle board comPuter within the recordinq unit 14 is then actuated in response to this control siqnal.
Stated differsntly, diqi-tal control data are entered at the location of the data acquisition module ~3, the control microcomputer thereof is operated to transfer the diqital control data into the shared diqital memory, and the trans~
ferrinq microcomputer is operated to transfer the diqital iL2897923 control data from the shared diqital memorY to the monitored data output port of the data acqui3ition module for trans-mission over the communication conduit to control another device connected to the communication conduit.
Just as the recordinq unit 14 can be controlled by siqnals qenerated at the display unit 2, the display unit 2 can be controlled by siqnals qenerated at the recordinq unit 14. This is done bY reversinq the aforementioned operation in that the transfer microcomputer, includinq the micropro-cessor 70, obtains data from the communication conduit and stores the control data in the random access memorY 50. The microprocessor 70 causes a status word in the memory 50 to be incremented or otherwise chanqed so that the micropro-cessor 52 responds to the chanqed status word to retrieve the diqital control data from the memory 50 and to provide a control output siqnal in response to the diqital control data. For example. the microprocessor 52 would cause one of the analoq switche3 62 to open or close, thereby causinq some external unction to occur in response to the chanqed state of the switch. The microprocessor 52 could also cause an analoq output siqnal to be provided throuqh thP diqital to analoq converter means 6B to similarly control an exter-nal device. Such external devices could be related to controllinq the monitored operation so that the monitored characteristic is thereby chanqed.

.
, ~. .. ,; ' , ~

~2~37923 Calibration Still another operation of the present invention is the ability to enter multiple calibration points into each data acquisition module 43 so that each module responds accu-rately to an input received throuqh the connector means to which the various transducers are connectible. Such a calibration control means includes means for defininq within each apparatus more than two points of the predetermined response characteristic of the transducer detector means so that the data acquisition module is calibrated for non-linear chanqes in the predetermined response characteristic.
Tbe method by which this is implemented includes: enterinq calibration factors, such as via the keyboard 66, throuqh ~he microprocessor 52 into its random access memory 56;
receivinq a transducer siqnal from a transducer detectinq the monitored characteristic and connected to an apPrOpriate one of the inputs to which the voltaqe to frequency con-verter 42 and the amplify and square circuit 44 are connec-ted; and creatinq the diqital electrical siqnal to be transferred to the recordinq unit 14 in response to the transducer siqnal and the calibration factors. This further includes determininq whether the response of the transducer is linear.
To determine if the response of the transducer is linear, more than two known values of the monitored charac-teristic are applied to the transducer which is connected to the module 43. The response3 of the transducer to the known ~28~

values of the characteristic are displayed throuqh one of the displays 100, 102 operated by the microprocessor 52, and the displayed responses are compared to determine if the chanqes between test values are linear or non-linear. Each of the more than two known values of the characteristic and the corresPondinq responses thereto are then loaded into the memory 56 when the comParison of the displaYed responses indicates the response of the transducer is not linear.
In the preferred embodiment of the present invention, up to fourteen calibration points can be entered. So that the calibration factors, and other stored data, are continuously retained within the data acgiuisition module 43 even when no external power is beinq aPplied thereto, the method of the present invention further comprises continuouslY enerqizinq the random access memory 56. This is accomplished in the preferred embodiment by a battery 168 and its associated circuitry located on the random access memorY board 96 shown in FIGS. 9A-9B. Thus, even when the overall sYstem is de-enerqized, the battery 168 enerqizes the random access memory 56 so that the calibration factors are retained until other calibration factors are entered in their place.
The multipoint calibration routine can be simulated by drawinq a qraph of the transducer output. The number on the X axis is the frequency qenerated by the transducer, and the number on the Y axis is the pressure value represented by the correspondinq frequency. BY way of e~ample, assume a 4-20mA pressure transducer qenerates 2796 Hz at 0 psi and - ' ' ` ',. ;. , `
. , , i . , .

~3 13982 Hz at 15000 psi. These frequency points are deter-mined bY applYinq the known pressure to the transducer and readinq the display of the data acquisition module. Each readinq is- made by applyinq the pressure to the transducer, then pressinq the followinq sequence of buttons on the module's keyboard 66:

Cha~ ~Chan¦~ r ¦¦ RUN ¦
L PROG I L I L 1 1 OR L2 ¦¦ 6 ¦¦ 4 ¦¦ 8 I L6 I tl I

where 64 is the function code and 86 is the access code for the preferred embodiment.
once the points have been determined, the apParatUs is recalibrated by pressinq:

r I ~ I r Chan¦ ¦ Chànl r 1 1 I r I l T--~
¦ PROG ¦¦ 0 ¦¦ 1 ¦ OR ¦ 2 ¦¦ 6 ¦¦ 5 ¦¦ 8 ¦¦ 6 ¦ ~ I ¦

.. ..... _ _ . . . . .. _ .. _ _ . _ _ _ ._. _ Chan _ _ RUN
(Enter Freq 1) 0 0 2 7 96 ~
. .. _ .. __~ _ _ __ _ _ _.

(Enter Value 1) ~ ¦ ~ L ~ ~ ~ ~¦ ~ l .... . . , , _ _ Char Chan RUN
(Enter Freq 2) 0 1 .3 _ _ 8 2 H¦ ¦

I--------ll--cha-~r-----lr~---~~~~ll-~~~~--ll-~-~-~lrR~Nl (Enter Value 2) L ¦ L 1 ¦ L5~ ¦ ¦ L ¦¦ ¦ ~ l (Enter ~11 -Ir 11 Ir lr - -Ir IrRUNI

Code) ~ I L ~ L ~ L ~ L ~ L ~ l _ l ~ l (Enter I I I I I I I I I I f ¦ ¦ RUN ¦
Finish Code) ¦ 9 ~ L ~ L H L I
To calibrate for a flow rate the function code is 65 and the access code is 8~. In addition to enterinq frequencies and correspondinq values. a meter factor and a barrel con-version factor are entered. For example, press:

¦ PROG ¦¦ 0 ¦¦ 1 ¦¦ 6 ¦¦ 5 ¦¦ 8 ¦¦ 6 ~ t - I I
(Enter Freq 1) ~ ~¦ I L o ~ ~ L ~ L L
_ . . _ (Enter Value 1) ~ j ~ r~ L~ E~LI

. . . -_ TEST RUN
(Enter Meter 0 0 5 5 7 :~
Factor) . _ _ _ P ¦ _ _ ¦ Cha~l TEST ll Cha~ r I ~ I r IIRUN
(Enter Bbl 1 _ 2 8 4 6 Conversion) _ __ ~ _ ____ _ (Enter Finish I 9 ~ L~ r ~ I Ll L~
Code) .

(Enter Finish ~ ~ L I ~ ¦ RUN ¦
Code) _ _ _ _ The apparatus is now calibrated for a flowmeter for meter factor of 55.7.
In the preferred embodiment calibrations must be in psi, : ~

barrels/minute, and lbs/qal to use the recorder unit cor-rectly. If units other than these are to be disPlaYed, scale and offset factors described below can be used. A decimal TESI
point is entered usinq the keY.
.P I .
The calibration of a data acquisition module 43 for use as a density monitor is different from calibrations for pressure and flow rate. About eiqht data points should be used ~or densometer and rate calibxation:
PRESS

(Enter Freq 1) ¦ I ~ r 1 ~3 ~ ~

~ ~Enter Density 1) rO ¦ rO I ~ I r O
(decimal point assumed I I I I I I L .. .l between second and third diqits) I ¦¦ Cha~ Chan¦¦
(Enter Fr~q 8) 1 . . - - ''---'-- -'-'---'-'---I
~Enter Density 8) O 8 3 ~ (i.e., 8.33 lb/qal) __ ____ _ (Enter Finish _ Code) O O O _0 _ _ _ __ _ . ~
(Enter Finish _ ~
Code) O O O L _ _.__. __ _ __ Besides multipoint calibration, the data acquisition module has other codes which can be used to chanqe calibra-tion:

::
.. . .
,: ,:

. : ~: , `
,: , .,," . , - . , 1~7~:3 1 sec freq. from densometer 10 sec freq from densometer ... . .. . ...... . ~ . ._ C2ha~ Chan ~ 6 1 I ~¦ ¦ Cha~ ¦RUN ~1 .1 - 1I l__ -~ L
100 sec req. from densometer Chan¦ ¦ Chànl r ~Chan¦ ~RUN ¦
2 ¦ ¦ 2 ¦ ¦ 6 ¦ L ¦ ¦ 7 Minimum Diqital Analoq Converter (DAC) Voltaqe h ~
.. _ ., .. ... . _ _ . . ...... _ _ .
Maximum DAC Voltaqe ... . _ __ ~ ~I L ~ 1 7 .. . _ .. _ _ . .... _ . _ 500 sec freq averaqe , .. . . .. ... ..... .

I 2 ~ ~ ~ 6 ~ ~ 7 ¦ ¦ 7 ¦ ~ Cha~ ~ RUN
_ ¦ ¦ _ _H¦
Display calibration points ... . .. .. ..... .... ..... . . ..
¦ 3 ¦ ¦ 6 ¦ ¦ 6 ¦ 7 7 ~ Ch New LO CAL data Enqineerinq units can be chanqed for display purposes.
The preferred embodiment of the system uses Enqlish units for communicatlon and storaqe on diskette (i.e., psi, bpm, . .
; . :. . .
,.' .
-- .
.

-46~
lb/qal, F, pH). If it is desired to display in some other units then SCALE and OFFSET routines can be used. It does not matter which one is entered first. Offset should be zero for everYthinq except temperature.
To chanqe displayed scale, press:

.... ... . , . _ _ , , . _ _ _ . _ . ... .. .
Chan Chan RUN
PROG 0 1 or 2 9 0 8 6 H¦
. . . . . ... . .. _ . .. . . . .
The current scale for Channel 1 or Channel 2 is now dis-RUN
played; if it is correct, press H¦ , otherwise enter a RUN
new six-diqit scale and press . For example, to chanqe to Meqapa cals ~MPa) enter L~ ¦ ¦ ~ ~ 6 ~ ~8 ¦ 9 ¦¦ I ~ where P is the decimal point ~.00689 x psi = MPa).
. ~ . . .. . .
Chan TEST
o chanqe to litres/min enter L 1 1 1 5 I 1 8 Codes for enqineerinq units are:

From ToMultiply bY

PSI MPa .00689 PSI Bar .06804 BPM Gal 42 BPM Litres/Min 158.97 BPM M3/Min .15877 .....

... : `:' ' , , ,"

~2~3~923 LB/GAL KG/M3 119.94 LB/GAL Spec Gravity .11984 F C .55556 -In some cases, an offset is also required as in the-con-version from F to C (C = .55556 *F 17.778). Current software only allows for neqative offsets, therefore, for the temperature conversion example, press:

Cha~ I Cha~ Chan¦¦ l --- I RUN

¦ PROG ¦~ J ¦ 1 ¦ OR ¦ 2 ¦¦ 9 ~ ~ 6 ¦

.. . . ..
1 1 ¦ 7 ~ 7 ¦ 7 8 The units are confiqured so that a pressure data acquisition unit accepts two 4-20mA units. A rate/total data acquisition unit accepts two frequency inputs which it combines and displays as a combined rate on Channel 1 and a combined total on Channel 2. To check a unit tYpe, press ¦¦ Cha~ ¦ Chan¦ ~ ¦ ¦ ¦ ¦ RUN ¦
¦ PROG ¦ ~ OR L2 1 ~ ¦l ¦ La~

~ number will be displayed in the far left diqit of the Channel displaY: 04 = Pressure 05 = Combined Rate 06 = Combined Total 08 = Sinqle Rate 09 = Sinqle Total 10 = U-Tube Densometer If the channel is to be chanqed to another type~ press a two-diqit number 04, 05, 06, 08, 09, 10 correspondinq to the ~ N I
codes above and ~ L I . If the type is okaY~ just press ¦RUN ¦
r~ I

", , , :, ~, .
: :~. . :
- , : ~ ' `": `

~2~

The modules 43 are initially confiqured so that the pressure unit address = 1, rate/total unit address = 2 and density unit address = 3.
To chanqe this address, press ~ ¦¦ Chan¦~ RUN ¦
PRG I I ~ ~ I L 7 The current address will be displayed. To chanqe to another address, press a two-diqit number less than 32. No two rRUN ¦
units may have the same address. Tben press ~ ~ .
To use a data acquisition unit to measure sand concen-tration, base fluid density and proppant coefficients must ~ RUN ¦
be entered. First, press I 1 1 ~ ~ to enter sand concantration. If the base fluid is in the densometer now ~-nlr~'`'~'`lr'-R'U-N''I
and is displayinq the correct value, press to use this number for base fluid density. If the base ~luid density is known. it can be entered directly by .... ... ..
Chan pressinq 1 S and four more diqits xxxx where they represent the base fluid density to two decimal places. For ¦ Chan¦
example. if the base fluid i3 8.75 lb/qal. press L 1 . ~- .~ .

. - . . .
..: ..:

,. .. : : :
: ., , ~287g~3 1 ~ r I rRUN I
5 ~ ¦ 0 ¦ ¦ 8 ¦ ¦ 7 ¦ L5J ~ . Make sure to press ¦ RUN ¦
to complete any operation. Next, enter the correct H¦ ¦ Chan¦¦ ¦¦ RUN¦
proppant coefficient. Press ~ ¦ 6 ¦¦ ~ to use sand Cha~ _ RUN¦
(0.456) as the proppant. Press 1 7 ~ to use SUPER PROP~ proppant (0.322). For anY other coefficient Cha~ RUN 1 press 1 ¦¦ 8 ¦xxxx ¦- ¦ where the x's represent the ... . . .
coefficient to 4 decimal places (e.q.. if your proppant co-Chan Cha~ __ efEicient is .1500, press 1 8 1 5 0 ¦¦ RUN ¦
H¦ ¦
For settinq the internal clock, first check to see if the time is correct by pressinq ~ PR~
RUN
O 8 6 ¦. The module then displays HH:MM:SS
.. I ~ L YY:MM:DD
To chanqe:
. . ~
_ r Irchanlr 1l Ir a. Year -- PROG ~ ~ 1 5 11 1 11 8 ¦ ¦ 6 Where YY are the last two diqits of the year.
I i r I I 1 r li Chan~ RUN ~
b. Month --Where MM are the two diqits of the month.

: :. - .: .
: . :
- - ::: . . .
'~ `"' .
~:

c. Day -- ~ PRO& ~ D ~ ~ D ~ 5 ¦ ~ L ~ ~ ~ U~

Where DD are the two diqits of the daY.

d. Hour -- ~ i 4 Where HH are the two digits of the hour (24-hour clock).

e- Minutes -- ¦PROG ¦~ M ~ 5 ¦ 5 Where MM are the two diqits of the minutes.

f Seconds -- ¦PROG ~ Ls L~
Where SS are the two diqits of the seconds counter.
The followinq error codes are used in the data acquisi-tion module:
CODE DESCRIPTION
H A L P 1 - Divlde by zero ~ A L P 2 - Heap Overflow H A L P 3 - Strinq Overflow check H A L P 4 - Array and Subranqe Check H A L P 5 - Floatinq Point Overflow H A L P 6 - Floatinq Point Overflow When anY PASCAL error is found, one of these codes is I RUN I -displayQd. Press for a COLD ST~RT of a data H¦
acquisition module. If an H appears as the most siqnificant diqit in a channel, then an overranqe has occurred on the .
.
.: : .
. ' ~ - ''' ' ',` ~ ' ' ' ' , ' `' ;. , : ' .. ' ' .

~8~3 display. Either reduce the input or recalibrate. An L is displayed in the lower left corner of Channel 2, if any unrecoqnizable codes are entered.
The foreqoinq and other command, or function, codes of the preferred embodiment include:
50 Display Time 64 Measure Input Frequency Sl Set Year 65 Multipoint Calibration 52 Set Month 70 Channel Type 53 Set Day 71 Box Address 54 Set Hour 90 Scale Factor 55 Set Minute 91 Offset Factor 56 Set Seconds 99 Cold Start 00 Density Mode 22 100 Sec Frequency U4 AUTOCAL Air 23 DAC Minimum 05 AUTOCAL Water 24 DAC Maximum 06 AUTOCAL Lo Cal 25 500 Sec Frequency avq U7 AUTOCAL KCL 36 Display Calibration Points And Concentrate 37 New Lo Cal Data 14 Base Fluid 15 Ne~ Base Fluid (NOTE: Codes qreater than 18 16 Sand require 6771 access number 17 SUPER PROP~ after code. Then RUN) 18 New Proppant 20 1 Sec Frequency 21 10 Sec Frequency ,.~ ,, ~7~

Operatinq the DisplaY Unit 2 After turninq the power switch "OM" (see switch 170 in FIG. a~, the three data acquisition modules 43 will automa-tically start runninq usinq information previouslY saved in the respective battery backed-uP random access memories 56 durinq the calibration procedures. If anY of the modules has flashinq 8's in a display 100, 102, the RAM 56 is not workinq correctly and needs to be calibrated.
The operator can perform five major functions on a data acquisition module:
zero a pressure channel;
Zero a total volume channel;
Enter setpoints to control analoq switches;
Press test button; and Enter event codes.
A. Zero a pressure channel (NOTE: Pressure trans-ducers must be connected to the display unit) Thi~ is done when a new transducer is used or if minor pressure chanqes have occurred. Press ZERO then select the Chan Cha~ RUN
desired channel, l or 2 ~ and H¦ with zero pressure on the transducer. AnY pressure offset on the channel selected (l or 2) will be zeroed.
B. Zero a total volume channel ¦ ZERO¦
To zero the total volume counter, press ~ then Char I RUN _ 2 1 ~ l for total volume displaY.

. ~. ..
~, . .

, : ~: ' i' ::' ' ';

.

~8~

C. Enter setpoints for pressure or rate to control analoq s~itches.
Setpoints can be used to control pumpinq functions.
~hen an analoq switch closes it can be used to triqqer an alarm horn or even shift a transmission to neutral. When the displayed value in a channel exceeds the setpoint stored in memory for that channel, the relay closes. BY pressinq ¦ SET A¦¦ Chan¦ RUN ¦
¦ A~ I ¦ , the current setpoint for switch 1 is displayed (e.q., if the setpoint is 10000 psi you will see "lOOOP" where P represents the decimal point.) If the set-point needs to be chanqed, press five zeros, then the new RUN ¦ ¦ RUN ¦
number then I ¦ , otherwise just press ¦-- ¦ . To SE~ B Chan RUN
control switch 2, press ~ 1 H ¦ (chanqe the SET A Chan RUN
number the same way as for switch 1). A ¦__ __ _ controls switch 3.
TEST
D. Press test button. Pressinq P~_ performs a routine test o~ the module's memory and displays. First an EPROM sumcheck will be performed. If the EPROM is okay, the number 24737 will be displaYed on Channel 1. Then a RAM
check will be done with the result displayed as a flashinq number on Channel 2 (the number displayed at the end of a ` ~ :

' 12~

RAM check should be 63036). If the number is less than 63036. the RAM 56 is no lonqer 100~ functional and the unit should be used only with caution. (NOTE: The RAM 56 is used to store calibration and job data. If it is not completely functional, this could result in loss of job data). If this test passes. a series of walkinq 8's will move across the displays and the test will be complete. The walkinq 8's check the seqments of all display diqits.
E. Enter event codes: Event codes are used as land-marks in the sequence of monitored events. AS measurements ar~ bein~ recorded, the event codes can be,entered as theY
occur durinq the job.
The followinq codes are available.
CODE EVENT CODE EVENT

TOP PLUG DROPPED
NOTE: Codes 63. 65. 67 can be used for anY special event as needed. Code 69 will stop the recordinq system and print a job summary. Code 42 will stop the recordinq process. Code 68 will restart the recordinq after a job pause from code 42.

~, ., . , " . .

,.; ~
' ,~, ' " , ,. ' - ` : ~: ' ,,, ;.;.:
,...,. ~
. . . . .
, . ... . . .

- " ~287923 I~o enter an event code, press ~ , then the two-RUNdiqit code, and ~ .

The current version of the data acquisition module adapted for monitorinq densitY operates a little dif-rerently than the pressure and rate data acquisitlon units.
To be sure the density unit is calibrated properlY before runninq a iob, one of the followinq auto calibration proqrams can be run (the densometer must have the correct fluids in it and be connected to the data acquisition module):

AUTOCAL with air in densometer - Press ~ 0 AUTOCAL with water in densometer - Press ~ ¦ L 5 ¦-- ¦

AUTOCAL with air in densometer and LO C~L knob pulled out and turned CCW - Press ~

"' ~8792:3 AUTOC~L with 2% KCL ~8.44 lb/qal) in densometer - Press RU~
After the H l button is pressed the densometer will take samples of the fluid for 200 seconds and will then return to normal operation with new calibration data.

OPeratinq the Recordinq Unit 14 Turn "ON" the power switch (switch 172, FIG. 12) for the recordinq unit 14. Insert a diskette into disk drive A and a data disk into disk drive C. To playback information recorded on previous jobs, insert the aPPlicable job data disk into disk drive C.
~ rO perform a function with the recordinq unit 14, one of the followinq menu items is selected:
*************************MAIN ME~U*************************
- Start Job 2 - Setup Strip Chart 3 - Tabular Playback 4 - Format Disk 5 - Print Title Paqe 6 - Return to DOS
7 - Help 8 - Data Acquisition Unit 9 - Playback Strip Chart 10 - Data Acquisition Playback I~ you want to:

A. Start Job - Press 1 and ¦ RETURN¦ . The recordinq sYstem waits for job start (code 41). It will now start recordinq data and printinq a strip chart of the ..... . .: . , . ., .... . :

:~ .'. '' ..... '` ""~ ' , , . . .
- , : .. . :: :
, . . ~ , .

~287~

selected channels. After pressinq the "1" and the "RETURN" buttons, the printer ~ill type "YOU HAVE
SELECTED l-START JOB ARE YOU SURE (Y/N)", type YES if this is the correct function. The only way to qet back to the Main Menu i9 to press 69 which is the event code for job end. AnY of the other event codes maY also be entered from the keyboard 150 while a job is beinq recorded. All other keys are iqnored.

B. Setup Strip Chart - Press 2 and rRE;~URN ¦ . The strip chart can be calibrated by defininq which of the moni-tored channels should be displayed on the three chart spaces available as the output of the printer 152.

C. Tabular Playback - Press 3 and ¦ RETURN_¦ . This displaYs data previously recorded on a job disk.
The computer asks the nature of the data to be printed:
1. 1 sec data 2. 10 sec data 3. 30 sec data 4. 1 min data 5. 10 min data Select the number ~1, 2. 3. 4 or 5) of the desired time . .
interval, then press ~RETURN ¦ . Then select the four chan-nels to be displayed in tabular form.
Next, select the enqineerinq units to be displaYedO
At this Point the proqram will automaticallY start printinq a tabular chart.

D. Format Disk - Press 4 and rRETURN ¦ . This will cause the disk in drive C to be formatted.
E. Print Title Paqe - Press 5 and ~ URN ¦ . The printer .

' ' ' ' . ,: .
.,~. . :::

~L~87~

will qenerate a title paqe. After it is done, it will wait ~or the job start code. Press 1 and ¦ RETURN ¦ .
F. Return to DOS - Press 6 and ~ TURN ¦ . This enables the recordinq unit 14 to be used as a computer i~ a CP/M
development system disk has been inserted in drive A.
This allows the proqrams listed above to be run.

G. Help - Press 7 and rRETU~N ¦ . This displaYs basic operatinq instructions directlY from the disk.

H. Data Acquisition Unit Dump - PRESS 8 and ¦ _ T_RN ¦ .
This qets data stored in the RAM 56 in case it could not be stored on disk durinq a job. A set of data points is stored in the data acquisition module every 10 seconds ~-hich tells the hiqh, low and 10 second averaqe of each channel value and total.
I, Playback Strip Chart - Press 9. The recordinq unit 14 will qenerate a stripchart identical to the real-time one made durinq ths iob unless the stored values are chanqed throuqh operator control.
J. Data Acquisition Playback - Press 10 - This plays back the data acquired from the Data Acquisition Unit Dump in tabular or strip chart modes.

Conclusion The foreqoinq describes a preferred embodiment of the present invention as presently developed; however, modifica-tions have been contemplated. With respect to the display :- : . ., - ........... - ,; . :::: :, , : :~ -:
,. . :
. .

~lZ~37~

unit 2, it has been contemplated that an intrinsically safe display unit be developed to operate in hazardous environ-ments. It has also been contemplated to implement a nitro-qen flow analYzer sYstem usinq one of the data acquisition modules, and to add self-test proqrams to the data acquisi-tion module to simplify troubleshootinq. With respect to the recordinq unit 14, a plaYback proqram could be modified to add strip charts which can be displayed usinq the whole width of the paper for one value (in the current embodiment, the chart is divided into three sections to make iden-tification of different value lines easier) and to add plottinq of all three values usinq the full width of the paper for better chart resolution. Self-test proqrams could be added to simplify troubleshootinq; more detailed assistance instructions could be incorporated within the proqram; and the capability to enter customer data from the keYboard could be added.
In summary. the computerized system of the present invention, specifically adapted for recordinq cementinq data at an oil or qas w~ll site, qathers siqnals from up to 32 sensors throuqh interconnected display units and stores the information on a sinqle mlniature diskette located remotely ~rom the site of the operation. The present invention simultaneously makes a chart of this data usinq a standard computer printer to qenerate a chart similar to ones pro-duced by an analoq pen recorder. This enables print times, dates, actual data value and other specific alphanumeric ' ,. ,,:

.. , ... ~

~87~2;~

information to be printed alonq with the qraphical represen-tation. The use of this system will improve quality control of the monitored process and provide data needed ~or analy-sis of problems which occur within the operation.
Particularly unique within the system is the implemen-tation of a local area network desiqn which in the preferred embodiment uses a portion of the SDLC industry standard to reliably move data from one location to another~ This per-mits a number of ruqqedized displays to be placed close to their transducers while allowinq the more sensitive printer and diskette drive to be placed at a relatively far distance from the monitored operation environment. The flexibility of the local area network confiquration allows, in the pre-ferred embodiment. up to 32 display units to be connected to a network qatherinq data from units as far away as 2,000 ~eet. Another unique feature is the desiqn of the data acquisition module which can be independently used as data monitorinq and system control devices which can be both locally and remotely operated.
Thus, the present invention is well adapted to carrY out the objects and attain the ends and advantaqes mentioned above as well as those inherent therein. While a preferred embodiment of the invention has been described for the pur-pose of this disclosure, numerous chanqes in the construc-tion and arranqement of parts and the performance of steps can be made by those ski,lled in the art, which chanqes are encompassed within the spirit of this invention as defined .. ..

:

. ' ~ " '''' , ~ ` .
~L28~9~:3 by the ~ppended claims.

. - - ~ . ...
.
,: :

.

Claims (17)

1. A data acquisition apparatus, comprising:
input means for receiving electrical signals from at least one transducer;
digital storage means for storing digital signals corresponding to the electrical signals received by said input means;
first microcomputer means, connected to said input means and said digital storage means, for transferring the digital signals into said digital storage means;
second microcomputer means, connected to said digital storage means, for transferring the digital signals out of said digital storage means onto a transmission line; and output means for controlling an analog switch in response to said first microcomputer means.

2. An apparatus as defined in Claim 1, further comprising digital to analog conversion means for providing an analog control signal to an external device in response to said first microcomputer means.

3. A method of acquiring data in response to a detected characteristic, comprising:
representing the detected characteristic as a digital electrical signal generated at a first location which is near where the detected characteristic exists;
operating a first microcomputer at the first location to transfer the digital electrical signal into a digital memory, wherein said operating a first microcomputer includes modifying a digital status word, stored in the digital memory, when the first microcomputer transfers the digital electrical signal into the digital memory; and operating a second microcomputer at the first location to transfer the digital electrical signal from the digital memory to a port connectable to a communication conduit extending from the first location to a second location which is spaced from the first location, wherein said operating a second microcomputer includes detecting when the status word is modified and commencing the transfer of the digital electrical signal in response thereto.

4. A method of acquiring data in response to a detected characteristic from among a plurality of characteristics to be detected, comprising:

representing the detected characteristic as a digital electrical signal generated at a first location which is near where the detected characteristic exists;
operating a first microcomputer at the first location to transfer the digital electrical signal into a digital memory;
operating a second microcomputer at the first location to transfer the digital electrical signal from the digital memory to a port connected to a communication conduit extending from the first location to a second location which is spaced from the first location;
operating the second microcomputer to transfer digital control data from the communication conduit to the digital memory; and operating the first microcomputer to receive the digital control data from the digital memory and to provide a control output signal in response to the digital control data for changing which of the plurality of characteristics is detected.

5. A method of acquiring data in response to a detected characteristic, comprising:

representing the detected characteristic as a digital electrical signal generated at a first location which is near where the detected characteristic exists;
operating a first microcomputer at the first location to transfer the digital electrical signal into a digital memory;
operating a second microcomputer at the first location to transfer the digital electrical signal from the digital memory to a port connectable to a communication conduit extending from the first location to a second location which is spaced from the first location;
entering digital control data at the first location;
operating the first microcomputer to transfer the digital control data into the digital memory; and operating the second microcomputer to transfer the digital control data from the digital memory to the port for transmission over the communication conduit to control another device connected to the communication conduit.

6. A method of acquiring data in response to a detected characteristic, comprising:

representing the detected characteristic as a digital electrical signal generated at a first location which is near where the detected characteristic exists;
operating a first microcomputer at the first location to transfer the digital electrical signal into a digital memory;
operating a second microcomputer at the first location to transfer the digital electrical signal from the digital memory to a port connectible to a communication conduit extending from the first location to a second location which is spaced from the first location; and wherein representing the detected characteristic as a digital electrical signal includes:
entering, at least once, calibration factors through the first microcomputer into a second digital memory at the first location;
receiving a transducer signal from a transducer detecting the characteristic; and creating the digital electrical signal in response to the transducer signal and the calibration factors.

7. A method as defined in Claim 6, wherein:
representing the detected characteristic as a digital electrical signal further includes, before the steps of entering calibration factors, receiving a transducer signal and creating the digital electrical signal, determining whether the response of the transducer is linear, including:
applying more than two known values of the characteristic to the transducer;
displaying the responses of the transducer to the known values of the characteristic through a display operated by the first microcomputer; and comparing the displayed responses to each other to determine if the displayed responses indicate the response of the transducer is linear or not linear; and entering calibration factors includes loading each of the more than two known values of the characteristic and the corresponding responses thereto into the second digital memory when the comparison of the displayed responses indicates the response of the transducer is not linear.

8. A method as defined in Claim 6, further comprising continuously energizing the second digital memory so that the calibration factors are retained therein until other calibration factors are entered through the first microcomputer.

9. A data acquisition apparatus for locally monitoring near a process at least one detected condition of a plurality of detectable conditions of the process and for making data corresponding to the detected condition available to a remote location spaced from the process, said apparatus comprising:
a single housing, including:
a receptacle member; and a cover member detachably connected to said receptacle member, said cover member having at least one display opening and a keyboard opening defined therein;
a keyboard mounted in said keyboard opening of said cover member;
display circuit means for providing a visual output observable through said display opening of said cover member;
control microcomputer circuit means, connected to said keyboard and said display circuit means, for receiving inputs from said keyboard and for controlling said display circuit means;

input circuit means, connected to said control microcomputer circuit means, for providing digital signals to said control microcomputer circuit means in response to a condition detected by an external detector connected to said input circuit means;
dual port random access memory circuit means for receiving data from said control microcomputer circuit means, said dual port random access memory circuit means including a first port connected to said control microcomputer circuit means and further including a second port;
a single information transfer conduit means for extending from said data acquisition apparatus to the remote location spaced from the process;
transmission microcomputer circuit means, connected to said second port of said dual port random access memory circuit means, for transferring data from said dual port random access memory circuit to said single information transfer conduit means;
means for mounting said display circuit means, said control microcomputer circuit means, said input circuit means, said dual port random access memory circuit means and said transmission microcomputer circuit means within said receptacle member; and means for connecting said single information transfer conduit means to said transmission microcomputer circuit means through said receptacle member.

10. An apparatus as defined in Claim 9, wherein:
said data received in said dual port random access memory circuit means from said control microcomputer circuit means and transferred from said dual port random access memory circuit means by said transmission microcomputer circuit means to said single information transfer conduit means includes digital encodings of said digital signals provided by said input circuit means; and said single information transfer conduit means includes a single pair of conductor means dedicated for transferring said digital encodings.

11. An apparatus as defined in Claim 10, wherein said single information transfer conduit means further includes a single pair of conductor means dedicated for carrying signals indicating the instants in time during which said digital encodings transferred on said first-mentioned single pair of conductor means are valid.

12. An apparatus as defined in Claim 9, wherein said means for mounting includes:
a display board having said display circuit means mounted thereon;
a control microcomputer board having said control microcomputer circuit means mounted thereon;
an input board having said input circuit means mounted thereon;
a local area network board having said dual port random access memory circuit means and said transmission microcomputer circuit means mounted thereon; and means for retaining said display board, said control microcomputer board, said input board and said local area network board in a vertical array within said receptacle member beneath said cover member.

13, An apparatus as defined in Claim 9, further comprising output means, connected to said control microcomputer circuit means, for outputting control signals in response to control information transferred over said single information transfer conduit to said transmission microcomputer circuit means and passed by said transmission microcomputer circuit means through said dual port random access memory circuit means to said control microcomputer circuit means.

14. An apparatus as defined in Claim 9, wherein said input circuit means includes:
first connector means for connecting with a first transducer defining the external detector;
second connector means for connecting with a second transducer defining another external detector by which a second condition of the process is detected; and digitizing means for connecting said first and second connector means with said control microcomputer circuit means.

15. An apparatus as defined in Claim 14, wherein said digitizing means includes:
voltage to frequency converter means, connected to said first connector means, for converting a voltage, applied to said first connector means from the first transducer:, into a first electrical signal having a frequency;

amplify and square means, connected to said second connector means, for providing a second electrical signal having a frequency in response to a frequency signal applied to said second connector means from the second transducer;
counter means for providing a digital signal to said control microcomputer circuit means in response to the frequency of a selectable one of said first and second electrical signals; and switch means for connecting a selectable one of said first and second electrical signals to said counter means.

16. An apparatus as defined in Claim 15, wherein:
said control microcomputer circuit means includes:
a microprocessor connected to said counter means and said first port of said dual port random access memory circuit means;
program storage means, connected to said microprocessor, for retaining program to operate said microprocessor; and random access memory connected to said microprocessor; and said apparatus further comprises:

serial transmitter and receiver means for transmitting information from and receiving information for said microprocessor separately from said dual port random access memory circuit means;
and parallel input/output means for providing local information transfer to and from said microprocessor.

17. An apparatus as defined in Claim 16, wherein said transmission microcomputer circuit means includes:
a second microprocessor connected to said dual port random access memory circuit means;
second program storage means, connected to said second microprocessor, for retaining a program to operate said second microprocessor;
second random access memory connected to said second microprocessor; and serial input/output means, connected to said second microprocessor and to said means for connecting, for communicating data from said dual port random access memory circuit means to said single information transfer conduit.