OPERATING STATE MONITORING SYSTEM FOR PROGRAMMABLE CONTROLLER

摘要

PURPOSE:To correctly monitor the operating state of a programmable controller with a monitoring device. CONSTITUTION:A programmable controller 1 is connected to a monitoring device 2 via a communication channel 3. The controller 1 is provided with a data latch part 15 which temporarily holds the data in accordance with the operating state of the controller 1. Then the controller 1 transmits the data held at the part 15 to the device 2 in response to the data transmitting request of the device 2. Thus the device 2 monitors the operating state of the controller 1 based on a received data. Meanwhile the controller 1 transmits the data to the device 2 and updates the data of the part 15 when the data are different from the data generated at that time point.