PURPOSE: To rapidly clear up the fault cause of an automation equipment, etc., by receiving a state signal of a sequencer program controlling the automation equipment, etc., comparing it with the data stored in a memory and detecting the presence of an abnormal state signal.

CONSTITUTION: When a sequence number from the sequencer and the state signal of an operation item corresponding to it are received by a programable operation display POD, they are read out through a CPU, and an incorporated memory is accessed making the sequence number an address. Then, the read out state signal to be originally is compared with a receiving state signal, and when they disagree, an alarm is generated, and the comparison result for corresponding items between the sequence number and a step number is displayed. Further, a forward switch, etc., of corresponding switch name displays the address such as corresponding numeral 4010, etc., according to the end of the operation according to the operation items at this time, and the presence of the abnormal state signal is detected instantly, and the fault cause of the automation equipment, etc., is investigation up rapidly.