| 摘要 |
PURPOSE:To prevent state change detection necessity/nonnecessity information from being destructed at the time of writing data in a new value are ad to attain the proper execution for the state change by providing a state change detection necessity/nonnecessity information area separately from the new value area. CONSTITUTION:The state change detection necessity/nonnecessity information S which has been in the new value area 5 is separated from the area 5 and the state change detection necessity/nonnecessity area 15 is independently provided. When a process information 9 is inputted as a CDT data 11 to a DMA device 3 through a CDT slave station 1 and a CDT master station 2, the device 3 inputs the information S from the area 15 corresponding to the data 11 and a corresponding data 12 in the area 5 from a CPU4. In corresponding to contents of the inputted information S (for instance, S=1), the device 3 compares the contents of the data 11 with those of the data 12, and writes them as a state change data 13 on a state change list 6 together with a state change address if said data are different. Thus the destruction of the state change detection necessity/nonnecessity information S can be prevented, and the processing for the state change and the modification of new value data can be properly made. |
