M12 connector coding guide
M12 connectors are not interchangeable. Each code (A, B, C, D, K, L, S, T, X, Y) defines a unique keyway to prevent mismating — using the wrong cable can damage equipment. Here is the cheat sheet.
Quick reference
- A-code — Sensor & actuator, DC power, 1G Ethernet. 3 / 4 / 5 / 8 / 12 pin.
- B-code — PROFIBUS DP, Fieldbus. 4 / 5 pin.
- C-code — AC power (up to 630V). 3 + PE pin.
- D-code — 100 Mbit Ethernet, PROFINET. 4 pin.
- K-code — AC power (up to 630V, 16A). 4 + PE pin.
- L-code — DC power (up to 63V, 16A). 4 + FE pin.
- S-code — AC power (up to 630V, 12A). 3 + PE + 2 pin.
- T-code — DC power (up to 63V, 12A). 4 pin.
- X-code — 10 Gigabit Ethernet, Cat6A. 8 pin.
How to choose
Match the code to the protocol and current. The keyway (not the thread) determines if a cable can be inserted. For industrial Ethernet up to 1 Gbit, D-code is the standard; for 10 Gbit, X-code is required.
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