Digital PLC:
Digital PLC is mainly used to control switching quantities, such as switches and buttons. The input and output signals of digital PLC have only two states, namely ON and OFF, corresponding to logic 1 and logic 0.
Analog PLC:
Analog PLC is mainly used to control continuously changing physical quantities, such as temperature and pressure. The input and output signals of the analog PLC are continuously changing signals within a certain range, and the analog signals can be converted into digital signals by an analog-to-digital converter for processing.