The procedure for controlling an air compressor using a Siemens S7-200 PLC (6es7212-1BB23-0XB0) is as follows:

Hardware configuration

Connect the pressure sensor signal to the analogue input of the PLC (EM231 module needs to be extended), the start-stop button and overload signal to the digital input terminals (I0.0-I0.7); and the output terminals (Q0.0-Q0.4) to connect the contactor coils and the alarm indicator.

Programming

Write ladder logic in STEP 7-Micro/WIN:

Read the pressure value and compare it with the set range, trigger Q0.0 when the limit is exceeded (compressor start/stop)

Monitoring the overload signal (I0.5) triggers Q0.1 (fault alarm) and stops the machine.

Setting automatic/manual mode switching (I0.6)

Safety commissioning

First disconnect the load test logic action, confirm the pressure threshold, delay protection parameters (usually set 0.5-1MPa start-stop, 30 seconds delay to prevent frequent start), and finally run with load and monitor the current stability.