PURPOSE: To speedily perform the switching control of a duplex part even at a miniaturized equipment by disconnecting a present line control part, which is judged as a fault, from a normal auxiliary line control part by using a host processor.
CONSTITUTION: When the down of a present line control part 3-1 is detected, a host processor 1 performs a present instruction to a normal auxiliary line control part 3-2 and the auxiliary line control part 3-2 performs control by using an inter-system transmitting means 4 so that the present line control part 3-1 turned to the fault can be forcedly disconnected from the interface of a shared line connection part 5 and set as the auxiliary system. Thus, even when the interface of the host processor 1 and the fault line control part 3-1 is disconnected, present/auxiliary switching can be speedily performed.
YONEDA ISAO
YAMAMURA YOSHINORI
HITACHI JOHO NETWORK KK