PURPOSE: To detect a failure in cable connection in a plant control apparatus with a simple constitution by providing similar detectors for detecting whether the cable connection is normal or defective respectively on a plurality of controllers CR.
CONSTITUTION: When connection of a cable 3 is defective, an output signal 116 of a gate 11 provided on a detector 11 on a CR 1 indicates a low level L. A signal line 34 is for determining connection of a connector 17 wherein when connection of the connector 17 is disconnected, an input to a gate 112 is at a high level H so that an output signal 117 is at L. By periodically collecting the signals 116, 117 into a CPU 13 by a read instruction signal 118 via a bus 16, a failure in connection of the cable 3 can be connected, and it is further possible to determine whether the defective connection has occurred in the own CR 1 or in an opposite CR 2. When the defective connections is detected, all processing is suspended as well as a failure is informed outside via an input/output device 4 at the time of system startup, while during system operation, only means which can continue operation are permitted to continue processing.
ISAKA YOSHINOBU
KOBAYASHI MITSUAKI
KOBAYASHI MASAMITSU
| JPH0277762A | 1990-03-16 | |||
| JPS4720593A |