| 摘要 |
PURPOSE:To attain communication between other devices even if a faulty device is removed by providing a switch means driven by a device built-in power supply between a couple of terminals connected to transmission line of each device constituting a current loop for inter-device communication. CONSTITUTION:Transmission/reception circuits 31, 32, 33, processing circuits 41, 42, 43 and printed boards 21, 22, 23 as device main bodies including power supplies 51, 52, 53 are all connected to back panels 11, 12, 13 via connectors C1, C2, C3. In this case, contacts C and NO of relays R1, R2, R3 are connected, terminals t11, t12, t21, t22, t31, t32 are opened and the communication is enabled. If a board is taken out because of turning off of the power supply 53 of the board 23 or maintenance or fault, the relay R3 is not driven, the contacts C, NC are turned on, the terminals t31, t32 are short-circuited and turned off, the device is disconnected automatically from transmission line and bypassed so as to prevent the effect on other devices or disable communication. |
