| 摘要 |
PURPOSE: To discriminate a faulty interface unit without changing the output state of a correctly operating unit by inverting the input state of the interface unit having a faulty state. CONSTITUTION: If a fault occurs in one of interface units 30a to 30n, a fault display signal appears in a fault display output 35 of the faulty unit and is supplied to an interrupt input PINT or a microcomputer unit(MCU) no through a fault line 45. The MCU 10 turns on a transistor TR 50, and only the logical value of the data state of the faulty interface is inverted in response to the current charging to a fault display terminal 35 of each unit 30. The MCU 10 reads data values appearing in input terminals 25 of units 30 and determines the faulty unit by inverted data values. Thus, the faulty unit is discriminated without changing the output data values of units. |
