Related U.S. Application Data
Continuation of Ser. No. 143,540, Oct. 27, 1993, abandoned, which is a continuation of Ser. No. 732,071, Jul. 18, 1991, abandoned.
Int Cl.« G08C 15/08; G05B 15/02
U.S. CI 340/870.13; 340/870.39;
340/870.16; 340/870.21; 364/139
Field of Search 340/870.13, 870.38,
340/870.39, 870.40, 870.16, 870.18, 870.21;
U.S. PATENT DOCUMENTS
3,680,384 8/1972 Grindhehn .
4,001,703 1/1977 Saul et al 340/870.39
4,190,822 2/1980 Swarbrick 340/870.39
4,242,665 12/1980 Mate 340/870.38
4,607,247 8/1986 Sterling, Jr. et al 340/870.39
4,672,529 6/1987 Kupersmit 364/139
5,333,114 7/1994 Warrior et al 364/550
HART protocol, which was developed by Rosemount,
Inc., of Eden Prairie, Minn. Feb. 1990.
Primary Examiner—Donnie L. Crosland
Attorney, Agent, or Firm—Synnestvedt & Lechner
Integrated transmitters and controllers for use in monitoring process variables. A transmitter and controller for monitoring and controlling a process variable in a process control loop comprises a transmitter for producing a digital signal indicative of the process variable's state, and a digital controller supplied with the digital signal from the transmitter responsive to the digital signal, and further interfaced in a process control loop for controlling the process variable in response to the digitally communicated signal from the transmitter. Integrated transmitters and controllers described herein simplify installation and maintenance of industrial process control systems and place the controller functions at the process variable, thereby increasing control system efficiency.
3 Claims, 5 Drawing Sheets