| 摘要 |
PURPOSE:To suppress a system switching signal from an MSD (maintenance signals distributor) in a defective system by outputting default information that the MSD or its operation information transmitting system is defective as a sending gate signal for the system switching signal. CONSTITUTION:Usually, maintenance signal distributors MSD0, 1 are specified by the indicated orders of ''0'' and ''1'' systems from a central controller (CC), and when system switching data are inputted, a logical condition is found by AND circuits G1, G2 and stored in FFs 1, 2, respectively. Each output from the FFs 1, 2 is inputted to one input terminal of AND circuits G3, G4, and when default information is not outputted from maintenance scanners MSCN0 or 1, AND is found and system switching signal is outputted. If a fault is generated in said MSD or its operation information trasmitting system, the default information is stored in the MSCNs and the default information output turns the other inputs of the circuits G3, G4 for sending the system switching signal of the MSDs to logic ''0'' to suppress the sending of the system switching signal. |
