To output change information with the accuracy of fixed-cycle processing time of an electronic interlocking device main body by outputting the information stored in a memory at need corresponding to the information of the fixed-cycle processing.

An electronic interlocking device main body (a) is adapted to process in a fixed cycle of 200 ms. The change information and the cycle counter information can be sent from the electronic interlocking device main body (a) toward a signal monitoring device 1. The signal monitoring device 1 conducts editing processing for applying sequence data by an editing processing circuit 1b according to a clock signal at each second of an internal clock 1a and information from the electronic interlocking device main body (a), and then stores the same in a memory 1c. The stored information is output corresponding to the information of the fixed-cycle processing at need, and output according to the fixed cycle of the electronic interlocking device main body so as to perform fine analysis.