| 摘要 |
PROBLEM TO BE SOLVED: To prevent a communication module from transmitting erroneous data during starting of a data processing unit and in abnormal operation, the communication module processing data read out from the communication module mounted on a PLC to perform data transmission to a remote location in a monitoring system for monitoring a facility.SOLUTION: Internal software of a communication module 300 has an area for updating a value at fixed intervals during operation in a memory for a user program of a PLC 100. In this area, update is stopped during starting of the software of the communication module and in abnormal operation of the software. Data transmission is performed only when a counter is changing. In addition, when the counter does not change for a long period, restart of the communication module is performed. The stop of the communication and restart processing of the communication module are controlled by the user program of the PLC to allow a user to easily customize. |
