| 摘要 |
PROBLEM TO BE SOLVED: To allow a microcomputer in a PIO module to automatically detect and automatically handle a failure of a part of a transmission channel in such a case.SOLUTION: An input PIO module comprises a path changeover switch, an input/output circuit, and a microcomputer. The microcomputer sends a path change command to the path change switch on recognizing that an external signal s (s: an integer equal to or smaller than n) received through a second path s is illegal, and the path change switch once receiving the path change command that the microcomputer sends changes a connection opposite side of a primary-side contact n from a secondary-side contact n to a secondary-side contact n+1 and also changes a connection opposite side of a primary-side contact p (p: a variable satisfying n>p≥s) from a secondary-side contact p to a secondary-side contact p+1 when the integer s is smaller than the integer n, but change the connection opposition side of the primary-side contact n from the secondary-side contact n to the secondary contact n+1 when the integer s is equal to the integer n.SELECTED DRAWING: Figure 3 |
