Q: Wrong M12 A-Code 4P wiring — will it burn my PLC module?

A: Standard M12 A-Code 4Pin: Pin1 = V+ (Brown), Pin3 = 0V (Blue), Pin4 = Output (Black), Pin5 = Shield. If V+ and 0V are reversed: ① Modules with built-in reverse-polarity protection are normally safe; ② Cheap modules without protection will likely destroy the input circuit.

Recommendation: Install 24V reverse-polarity protection diodes in the cabinet; always confirm with a multimeter before mating. For molded cables, choose WIZ-CONN standard color-coding.