| 摘要 |
PURPOSE:To detect a failure of a slave station quickly and accurately at the side of a central monitor, by connecting photo couplers used for the monitor of operating state of the slave stations in series. CONSTITUTION:Transistors (TR) constituting each photo coupler 21, 22 and 23 are connected in series and connected to a relay coil (REL) 25 in a central monitor station. On the other hand, the change in the state of each slave station is detected with detectors (DET) 4, 5 and 6 and light emitting diodes in the photocouplers 21, 22 and 23 are illuminated in the normal state. Thus, since each transistor is in the state turned on, the relay coil (REL) 25 is excited and its contact 26 is selected to the OPR position. If a failure takes place in any of the slave stations, the detector (DET) detects it to turn off the TR. Thus, no current flows to the relay coil 25, the contact 26 is selected to the ALM position 15, and an alarm signal is generated. |
