Data transfer system for industrial control systems with diagnostic function for locating faults

摘要

The system has a ring structure with unidirectional data transfer without terminal addressing to the terminals (5) which are connected into the ring structure, together with a control station (7) of higher standing. Faults, e.g. open circuits (8), are located from the effect on the next terminal in the transfer direction, which fails to receive any further valid input signals and transmits a diagnostic message with a defined value. The value of the message is incremented by each successive terminal, so that the control station can determine the fault location from the difference between the current and predefined message values.