| 摘要 |
A PLC, when collecting device data of a controlled device for three times or more in the time of a single polling, compares previously acquired device data with currently acquired device data and stores the device data that have changed as changed data if the data are different, compares the changed data with the collected device data when transmitting the changed data to a PC with respect to each polling, restores the collected device data from the changed data if a total amount of the changed data is equal to or greater than a total amount of the collected device data and transmits the restored device data to the PC, and transmits the changed data to the PC if the total amount of the changed data is smaller than the total amount of the collected device data. |
