A: The red module of the plc cabinet is the input module.
Input module. The input module of PLC distribution cabinet programming has four main functions. The input module interface receives the signal from the process equipment at 220 V AC to convert the input signal to 5 V DC, the PLC can use the isolation block to isolate\/prevent fluctuations in the PLC after the signal is sent to the output, that is, the PLC input module has two main parts, namely the power part and the logic part. The two parts are electrically isolated from each other. Initially, the button is off. Thus, 220 V AC power is supplied to the bridge circuit through resistors R1 and R2. The bridge rectifier is used to convert the AC signal to the DC signal, while the Zener diode is used to provide low-voltage power to the LED. When the light from the LED falls on the phototransistor, it will work within the conduction region. Finally, 5V DC power is supplied to the processor.