Design of low-cost acquisition system for multi-channel analog signal for PLC and its application in temperature control system

Based on the concept of low cost automation, a kind of multi-channel analog acquisition program based on traditional analog circuits and digital I/O ports of PLC is presented in this paper, including hardware circuit, program design and principles of signal acquisition. Compared with the expensive PLC analog module, the system is designed with features such as low cost, easy to implement. This paper makes use of PID module of PLC and self-tuning technology, applying this analog acquisition program to the temperature control system, PWM signal is generated to control solid state relays to accurately control temperature, at the same time the data exchange between computer and PLC has been completed, the interface is friendly, the experimental results show the feasibility and practicality of the program.