| 摘要 |
PROBLEM TO BE SOLVED: To confirm the operation of an input circuit inexpensively by judging the normality or abnormality of circuit operation by a signal outputted corresponding to the opening/closing of the contact of a switching part provided at an input switching circuit part, and to save a space for confirming the operation of the input circuit. SOLUTION: In a normal state where operation is not confirmed, the contact TC1 of an input exchanging circuit EX is closed and a contact TC is opened. In order to switch inputting from this state, TC 2 is closed. Since each input circuit 1 to 3 is equivalent to the simulation of a state where contacts C1 to C3 are normally closed at this time, an operation judging means J1 fetches the signals A1 to A3 of the circuits 1 to 3 to investigates whether or not all the photocouplers PCA1 to PCA3 are lighted and conducted. Namely, it is investigated whether or not all the digital input circuits recognize the contacts C1 to C3. When all the circuits 1 to 3 are lighted, circuit operation is judged to be normal but when even only one of them is not lighted, the circuit operation is judged to be abnormal. Thus, the characteristic variation of the input circuits can simply be detected.
|
