0591926-A2 is referenced by 11 patents and cites 4 patents.

The present invention relates to a circuit which is connected to a two-conductor control system for a variable analog DC input and that also enables bidirectional digital communication along the two conductors for diagnostic operations of a transducer. The novel circuit includes a switch circuit that has a first position that provided the ability to accept both the variable DC analog signals and the bidirectional digital communication signals by presenting a first impedance for the DC signals and a second switch position for providing a second substantially higher impedance while using the same two-conductor system. The novel invention also includes an auxiliary analog input signal to the circuit which allows further control as a current feedback to a control algorithm in a microcontroller.; An auxiliary process transmitter can sense pressure, temperature, flow or some other process related variable and couple it to the circuit for control of the transducers. Finally, the novel invention includes a novel voltage regulator and a capacitive voltage supply for utilizing the voltage on the two conductors from the controller to also power the device.

Communication system and method.
Application Number
EP19930116079 19931005
Publication Number
0591926 (A2)
Application Date
October 5, 1993
Publication Date
April 13, 1994
Gassman George W
Grumstrup Bruce F
Seberger Stephen G
Fisher Controls Int
G08C 25/00
G08C 19/02
H04L 05/14
G08C 19/02
H04L 05/14
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