| 摘要 |
PURPOSE:To minimize the influence of a device failure upon a plant and allowing this adjustment controller to contribute to the safety operation of the plant by providing the controller with a backup logic circuit. CONSTITUTION:Since a digital output substrate 11 is turned off when the controller 1 is abnormal, an operation output 7 is switched to a set signal 16. The normality diagnosis of an analog output substrate (AO) 12 detects a substrate failure by reinputting the self-diagnosis (OS) of the substrate and an answer back signal 13 of a controller output signal 12 to the controller 1 and deciding whether an output requested by the controller 1 is generated or not. Namely, an output allowance error epsilon is set up while considering an error in the analog part of the AO 12, an error in the analog part of an analog input substrate(AI) 5 and a bit lacking error at the time of A/D conversion. Abnormality is detected by the following expression. ¦(AO output value) - (answer back value)¦<=epsilon. |
