PLC I/O & Wiring
PLC input and output circuits, field wiring, and systematic fault finding.
Articles
Troubleshooting a 4-20mA Signal That Reads Zero
A 4-20mA signal reading zero: tell a normal 0% from a real 0 mA fault, then check loop power, wiring, polarity, the input card, and the transmitter.
Why Does a PLC Input Stay On After the Sensor Turns Off?
A PLC input stuck on after the sensor releases is usually two-wire sensor leakage. Measure the terminal, check the input type, size the bleeder.