Keithley 2701

[DieLiz]

Hello,

I'm trying to blend two examples copied from the NI download in order to make my own application. My end goal is to acquire DC Voltage from two channel (101, 102) and DC Current from another channel (121) over a period of 3 second, synchronized whit the power supply that is ramping voltage and current.  

I downloaded the Keithley 2701 drivers, then I was able to communicate with the 2701 and test some of the examples. My goal is to combine the example "Keithley 27xx Performance" with the example "Keithley 27xx Advanced Scan". I was able to merge the examples together but I can't reach my goal. There are continuous errors popping up or the application does not do what I need.  

Attached you would see the two examples previously mentioned and my application. I would really appreciate any type of advice. Thank you so much!

-Diego- 

[cstorey]

Currently you configure the measurement for Function A, then overwrite that configuration with Function B.  The meter does not remember the first configuration, it just gets ignored, so the instrument is only ready for Function B measurements.

You need to configure the meter for DC voltage, measure on all channels, read data, configure the meter for DC current, measure all channels, read data.

If you want to measure DC voltage and current simultaneously you need two meters, and use a physical trigger between the two to synchronise both meters. 

Craig

[DieLiz]

Hi Craig,

Thank you so much for replying to my help request. In my previous message I did not mention that the Keithley 2701 has a 7700 board with 20 channels for voltages and 5 channels for others measurements (Input, Sense, Amp Com, and two for Amps). When I set the 2701 manually I can scan the two channels (101,102) for voltages and one channel (121) for Amps all together in one swipe.  

Here are some thoughts, from the example Advanced Scanner I got the idea of setting up "Scan List A" and "Scan List B" and concatenate them together. Setting up two List allows me to configure 101, 102 for DC Voltage and 121 for DC Current. Then checking with the Probe Watch Window the list that comes out is exactly 101, 102, 121 and checking on the 2701's display, it reads voltage for 101, 102 and it reads current for 121.

From the example Performance I got the other blocks for doing fast readings, memorize the data into the 2701's buffer and then read them once it's done. 

The problem is that I can't successfully merge those two together because the error -1074000000 pops up and the 2701 does not start to scan the channels. 

Any suggestion is welcome! Thanks in advance. 

Diego

[cstorey]

Ah, I see now.  The VI had the same channels being reconfigured for both purposes, but I guess those were just default values and not what you use when you run it.  So 101, 102 for DC Voltage and 121 for DC Current.    

That error message is a parameter out of range error.  Have you used Highlight Execution to see which VI generates the error? 

My guess is that its the Timing.VI where you set the aperture to 0.001s.  That's probably too short for auto-ranging current measurements.  Try setting it to 0.1s and see if the error goes away.  Then read the card specs to see what the minimum aperture is for each channel type.

The other problem I see in this VI is the use of "Multi-point measurement.vi (Buffer Subset)".  This does not initiate a measurement but retrieves current data in the buffer. And no where do you initiate a measurement, so buffer will always be empty.  Why not use the same read method as "Performance" and "Advanced"?  That would be "Multi-point measurement.vi (Direct)".

Here's a cleaned up VI where I try to implement a single scan using the setup you mentioned.  Debug the parameter out of range error and then see about running multiple scans, then extend it further as needed.

Craig

[DieLiz]

I tried to change the timing the iteration values as suggested and the error keeps appearing. Using the highlight execution and the single stepping, I saw that the error is generated in correspondence of the timing block.

Any suggestion is appreciated. Thank you for your help!

[cstorey]

Do a test where you just remove it.  Does the rest of the code work, even if not as fast as you would like?  

It might be that an aperture time is not compatible with the card or measurement type.   It might be that the measurement expects the timing value in power line cycles.  So try to use Power Line Cycle setting of the Timing.vi instead.  Minimum is usually 0.1 PLC, max 100 PLC.  1 PLC is ~16.7ms if you're on 60Hz or 20ms if 50Hz .  A lot of other instruments expect the value in PLC or time rounded to some equal PLC equivalent.

Again, check the card specs carefully.  I think each card has its own set of documentation.

Craig

[DieLiz]

Thank you Craig for you support!

I've tried to remove the Timing block and the code stopped one block before, also changing the Power Line Cycle setting did not make it working. The error ERR-1074000000 keeps appearing after the Timing block.

If there are other advises I'll be interested to try them out. I was also wondering if I should contact Tektronix or LabVIEW and ask for support, but I think it's a problem related only to my luck of LabVIEW's knowledge and not an hardware/software bug. 

[DieLiz]

P.s.: Attached is the error window.

[DieLiz]

I ran the code with the Single Step function and attached is a screen shoot with details.

[Carolynn.V]

Hello!

I have attached an article below that details troubleshooting steps for the error you are currently seeing. Walking through these steps will help determine if your device is successfully communicating with your computer.

"Error 1074000000 in LabVIEW When Using a GPIB Device"

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019ODGSA2&l=en-US