| 摘要 |
PURPOSE:To prevent an external output apparatus from malfunction or the like by checking write and read data, repeating writing and reading moreover at the inconsistency of both the data, and when the number of times of repeat reaches a prescribed value, outputting error information. CONSTITUTION:A programmable controller is constituted of a main operation part 1 and an input/output (I/O) part 2, the main operation part 1 consists of a memory part 11 storing a sequence control program or the like, a logical operation part 12 and an I/O control part 13 and the I/O part 2 has plural I/O modules 21, 22. In this case, said I/O control part 13 is provided with the 2nd memory part 131 having a write buffer B and a controller 132. The controller 132 reads out output register values in respective output modules 22 and checks the read- out data with write data. When both the data are inconsistent, data writing and reading are repeated again, and when the number of times of repeat reaches a prescribed value, error information is stored in the memory 11 and error display is executed. |
