Which M12 Coding Does My Network or Device Use?
Most devices need two connections: one for data or signals and one for power. Use this table to find both, then confirm against the device datasheet.
| Network or device |
Data or signal connection |
Power connection |
| Discrete sensors and actuators | A-coded, 3 to 5 pin | Carried on the same A-coded connector |
| IO-Link devices | A-coded, 4 or 5 pin | Carried on the same A-coded connector |
| DeviceNet and CANopen | A-coded, 5 pin | Carried in the bus cable |
| PROFIBUS DP | B-coded | See device datasheet |
| PROFINET field devices and I/O blocks | D-coded (100 Mbit/s) or X-coded (Gigabit) | L-coded on many I/O blocks |
| EtherNet/IP and EtherCAT field devices | D-coded (100 Mbit/s) or X-coded (Gigabit) | A-coded or L-coded, per datasheet |
| Machine vision cameras and 3D sensors | X-coded, 8 pin | Usually a separate A-coded power and I/O connector |
| Motors and small drives | See device datasheet | S-coded or K-coded (AC) |
Reading the Coding From the Part Number
Replacing a cable and only have the old part number? Several brands put the coding right in the catalog number.
| Brand |
Where to look |
Example |
| Baumer | The letter and number after CAM12 give coding and pin count | CAM12.A5 = A-coded, 5 pin; CAM12.D4 = D-coded, 4 pin; CAM12.X8 = X-coded, 8 pin |
| WAGO | The letter after M12 in the product description | M12A = A-coded, M12D = D-coded, M12L = L-coded |
| Turck power | The letter after P following the pin digits | FK44PL = L-coded, RKP46PT = T-coded, FK54PK = K-coded, FKFD44PS = S-coded |
| Turck Ethernet | The connector prefix | RSSX = X-coded (8 pin, Cat6A); RSSD and RSCD = D-coded |
| Leuze | The coding is listed in the product specifications as Encoding | Encoding = A-coded, B-coded, or D-coded |
Mating Rules That Prevent Wrong Orders
- Same coding on both sides. Each coding has its own keyway, so an A-coded plug will not go into a D-coded port, even when both are 4 pin.
- D-coded is not a Gigabit connector. D-coded M12 is rated for Ethernet up to 100 Mbit/s. A Gigabit camera or switch port needs X-coded cable end to end.
- Power codings are keyed apart. L, T, S, and K-coded connectors do not mate with each other, so match the coding on the power supply output, the distribution tee, and the device.
- Mixed-coding cables exist on purpose. Some PROFIBUS and adapter cables use a different coding or pin count on each end. Check both ends on the datasheet before you assume a cable is symmetrical.
- Check the ratings, not just the coding. Voltage and current vary by brand and part. For example, Turck lists its L-coded M12 power family at up to 14 A, while its T-coded cordsets are rated 63 V and its K-coded receptacles 600 V.
M12 Coding FAQ
How do I know which M12 coding I need?
Check the connection table on the device datasheet, which lists the coding letter and pin count for each port. If you are replacing an existing cable, Baumer, WAGO, and Turck part numbers often include the coding. For network devices, D-coded is used for 100 Mbit/s Ethernet and X-coded for Gigabit Ethernet.
Can an A-coded cable be used for Ethernet?
Not on a standard Ethernet port. PROFINET, EtherNet/IP, and EtherCAT field devices use D-coded M12 for 100 Mbit/s or X-coded M12 for Gigabit, and both are keyed so an A-coded plug will not fit. Use an Ethernet cordset with the matching coding, or an M12 to RJ45 cordset to reach a cabinet switch.
What is the difference between L-coded and T-coded M12?
Both are keyed for DC power, but they are not interchangeable. L-coded M12 includes a functional earth contact and is widely used to power PROFINET and EtherNet/IP I/O blocks. T-coded M12 is a 4-pin DC power connector. Match the coding printed on the device power port.
Which M12 codings carry AC power?
S-coded and K-coded M12 connectors are keyed for AC power. They are used for motors, small drives, and other AC loads. In this category, Turck's S-coded receptacles use 3 pins plus PE and its K-coded receptacles use 4 pins plus PE.
Is X-coded M12 backward compatible with D-coded?
No. X-coded M12 is an 8-pin connector with its own keyway, and D-coded M12 is a 4-pin connector, so the two cannot be mated. To link a D-coded device to an X-coded network, use a switch or a cable with the correct coding on each end.
