Design of a Multi-Channel PID Temperature Control System Based on PLC and Internet of Things (IOT)

In view of the temperature control system with Programmable Logic Controller (PLC) as the core, the main problems focus on the inability to realize wireless communication, remote downloading, poor temperature stability and poor anti-interference ability. A multi-channel Proportional Integral Differential (PID) temperature control system based on PLC and Internet of Things (IOT) is designed. It can not only adjust the temperature in real time. But also, the thirdparty cloud platform can be used through Message Queuing Telemetry Transport (MQTT) protocol, wireless data monitoring and remote control can also be carried out, and PLC programs can be downloaded remotely. Compared with the traditional wired monitoring system, it has great advantages and brings unprecedented convenience to the maintenance of the equipments. Based on the prototype, the multi-channel temperature stability and anti-interference tests, and wireless communication monitoring and alarm tests are carried out. The results show that the actual temperature of the system can change with the set value by PID control algorithm with the multi-channel heaters, and the temperature stability can reach ± 0.1 °C in steady state. In addition, real-time data such as temperature, voltage and current can be obtained through the cloud platform monitoring interface. And after triggering the alarm, the mobile devices (such as mobile phones) receive messages in real time.