Protected input/output circuitry for a programmable controller

Details Protected input/output circuitry for a programmable controller Protected input/output circuitry for a programmable controller

1984-06-04

1986-12-09

Pellinen, A. D.

Electricity: electrical systems and devices

Safety and protection of systems and devices

With specific current responsive fault sensor

361 57, 361 97, 361101, 361103, 364483, 330298, 330207P, H02H 3093

Patent

active

046283978

ABSTRACT:
Input/output circuitry is disclosed for use in an I/O system of a programmable controller. The circuitry is protected against overcurrents without the use of fuses or circuit breakers, and is automatically restored to normal operation following correction of an overload condition. Diagnostic signals are produced for monitoring the operating condition of the circuitry. The invention includes an insulated gate transistor (IGT) having a main current section carrying a majority of the load current and an emulation section which carries a fractional portion of the load current. The emulation section current tracks the total current at all times. A current sensor monitors the emulation section current and provides a signal representing the instantaneous load current. This signal is continuously compared with preselected reference levels to derive a set of diagnostic signals that are indicative of the operating condition of the circuit, and whether output loads are open or shorted, for example.

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Data sheets, RIFA Integrated Circuits PBD 3545 and PBD 3544 (2 pages each), RIFA-AB, Stockholm, Sweden.
"Smart ICS for Power Switching", Machine Design, May 10, 1984, pp. 60-65.
Digicable Manual, Direct Digital Industries, Inc., Lexington, Ky.

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