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M12 Connector Pinout and Color Code: 4-Pin, 5-Pin, 8-Pin and Coding Types
The M12 connector is the standard plug on industrial sensors, actuators, IO-Link devices and industrial Ethernet. "M12" is the 12 mm thread; the pin count and the coding (the key that stops the wrong plugs mating) tell you what it is for. Here are the pinouts you will meet most often.
M12 4-pin (A-coded): sensors and actuators
| Pin | Wire color | Typical function (3- or 4-wire DC sensor) |
|---|---|---|
| 1 | Brown | +V (10–30 V DC) |
| 2 | White | Second output, NC output, or diagnostic |
| 3 | Blue | 0V |
| 4 | Black | Main output (NO); C/Q line on IO-Link devices |
A 3-wire sensor uses pins 1, 3 and 4 and leaves pin 2 empty, so a standard 4-pin cordset fits both. These colors follow IEC 60947-5-2; most brands match, but always check the device datasheet.
M12 5-pin (A-coded)
Same as 4-pin, plus pin 5 (gray) in the center. Pin 5 is used for functional earth on some devices, a second signal on others, and the extra isolated power on IO-Link Class B ports. A 4-pin cordset will plug into a 5-pin device, but pin 5 will not be connected.
M12 8-pin (A-coded)
| Pin | Wire color |
|---|---|
| 1 | White |
| 2 | Brown |
| 3 | Green |
| 4 | Yellow |
| 5 | Gray |
| 6 | Pink |
| 7 | Blue |
| 8 | Red |
Eight-pin cordsets follow the DIN 47100 color sequence, which is different from the 4-pin code: pin 1 is white here, not brown. Pin functions depend entirely on the device (encoders, valve islands, multi-signal sensors), so wire from the device manual.
M12 4-pin D-coded: industrial Ethernet
| Pin | Signal | PROFINET color |
|---|---|---|
| 1 | TD+ | Yellow |
| 2 | RD+ | White |
| 3 | TD– | Orange |
| 4 | RD– | Blue |
D-coded M12 carries 100 Mbit/s Ethernet (EtherNet/IP, PROFINET, EtherCAT, Modbus TCP). For gigabit and faster, use 8-pin X-coded.
M12 coding types at a glance
| Coding | Used for |
|---|---|
| A | Sensors, actuators, DC power, IO-Link (3 to 12 pins) |
| B | PROFIBUS and some fieldbuses |
| C | AC sensors and actuators |
| D | 100 Mbit/s Ethernet |
| X | 1–10 Gbit/s Ethernet, 8-pin |
| S | AC power |
| T | DC power |
| L | Higher-current DC power, for example PROFINET power distribution |
The coding key is a small notch or rib in the insert. Different codings will not mate, which protects a 24 V sensor from being plugged into an AC or Ethernet port.
Male vs. female and reading the pin numbers
Sensors usually have a male receptacle (pins), and the cordset has a female socket. Pin numbering is mirrored between the two when you look at their faces, which is the most common reason for a "wrong pinout." Always check whether a diagram shows the male or female face.
M8 and other sensor connectors
- M8 3-pin: pins 1 (brown, +V), 3 (blue, 0V), 4 (black, output). Same colors and numbers as M12, smaller thread.
- M8 4-pin: adds pin 2 (white).
- 1/2"-20 UNF (micro-style): common on AC sensors in North America.
- 7/8"-16 UN (mini-style): heavier-duty power and AC connections.
Choosing a cordset
- Match size, pin count and coding to the device.
- Choose straight or right-angle to suit the mounting space.
- Pick the jacket: PVC for general use, PUR for oil and flexing (cable tracks), TPE or silicone for high temperature or washdown.
- Choose length, or a double-ended cable to run to a distribution block.
HTM offers M8, M12, 1/2-20 and 7/8 cordsets, double-ended cables and splitters in PVC, PUR, TPE and silicone. Browse HTM sensor cables and connectors and distribution blocks.
Frequently asked questions
Can I use a 5-pin cable on a 4-pin sensor?
Yes. The 5-pin female socket accepts a 4-pin male plug, and pins 1–4 line up.
Are M12 connectors waterproof?
Typically IP67 when mated and hand-tightened. Unused ports need a sealing cap.
Why does my sensor work on one cable but not another?
Usually a different pin assignment for pin 2 or 4, or a male/female diagram mix-up. Compare both datasheets.
Need a specific cordset? Call 1-800-724-4209 or request a quote with the connector, pin count and length.