ABNORMALITY DETECTING CIRCUIT FOR SEQUENCE CONTROL CIRCUIT

摘要

PURPOSE:To attain the automatic detection of the abnormality of a sequence control circuit with no reliance on the visual confirmation. CONSTITUTION:The changing order of the input/output signals set when a sequence control circuit 100 is normally working is stored in an internal memory of a CPU 202 included in an abnormality detecting circuit 200. Then a fact that the changed input/output signals are subject to the changing order of the internal memory is checked every time the change of contents of the input/ output signals is detected by the CPU 202. Thus the operation of the circuit 100 is confirmed.