INNER TEMPERATURE SENSING METHOD OF PROGRAMMABLE LOGIC CONTROLLER

摘要

The alarm signal is generated when the internal temperature of a programmable logic controller exceeds a preset temperature. The method comprises the steps of: (A) detecting internal temperature of a PLC using a temperature sensor (6); (B) sending temperature data to a microcomputer (1) using a schmidt trigger (7); (C) discriminating that the detected temperature exceeds a preset temperature; (D) operating a PLC normally when the detected temperature is below the preset temperature; (E) discrimining that a PLC is programmed to be shut down; (F) driving an alarm buzzer (9) and operating a PLC normally when a PLC is not programmed to be shut down in the step (E); and (G) resetting an interface unit (4) to shut down a PLC for driving a buzzer when a PLC is programmed to be shut down.