PURPOSE: To prevent o an important event attended with a fault of an address setting means even when the fault of the address setting means takes place or a station address is set in mistake in the communication system implementing communication control of a token pass system.
CONSTITUTION: A communication controller CS is provided with an own addressed token detection means 12 detecting a token to itself via a bus, a watchdog timer means to which a prescribed time is set and time measurement is started when token reception is detected, a reception discrimination means 14 discriminating whether or not a frame from other communication station is received within a time when the watchdog timer means 13 expires, and when a frame is received within a time till the watchdog timer means 13 expires, it is discriminated to be a duplicate address error and the subscription to a bus is stopped.
MIZUMORI TAKASHI
EHASHI HIROMICHI
