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M12 Coding Cheat Sheet

Based on §8.1 of the M12 deep dive — this page is the print-friendly extract; the deep dive is the authority, and the exact part's datasheet outranks both.

Coding keyways and insert geometry prevent mismatched codings from mating — exact geometry per IEC 61076-2-101/-109/-111 and the manufacturer drawing. Standardization improves cross-vendor interoperability, but it does not make it automatic: exact code, pin count, gender, shielding, sealing, torque, and cable-assembly details still need verification against the specific part.

The codings​

CodePinsPrimary usePractical note
A3/4/5/8DC sensors, actuators, I/O, IO-Link, some CAN4-pin A-coded is extremely common for basic industrial sensors. IO-Link = a point-to-point digital sensor/actuator protocol carried over the same unshielded 3–4 wires.
B5PROFIBUS and similar fieldbusLess common in new systems; keyed differently from A
D410/100BASE-TX industrial Ethernet4-pin; commonly used for 10/100 Mbps; not rated for GbE/10G
X8Gigabit / 10G-class industrial Ethernet8-pin, shielded; used for GbE/10G applications
L4+FEHigher-current DC power (e.g. PROFINET power)4 power contacts + FE (functional earth) per DIN EN 61076-2-1111; vendor example rating 12 A/16 A at 63 V DC — distributed I/O power, higher current than A; verify exact rating by catalog
T4DC power (dedicated)4 contacts per DIN EN 61076-2-1111; vendor example rating 12 A at 63 V DC — verify exact rating by catalog
S4/5AC powerApplication-specific; verify by catalog
K4+PEAC power4 power contacts + PE (protective earth); the 630 V AC class is an example configuration per IEC 61076-2-1112, not a universal M12 rating — verify exact current, voltage, and pinout by standard edition and catalog/application

Schematic face views of M12 A, B, D, and X codings

Schematic face views of the four most common codings.

Which standard covers what​

  • IEC 61076-2-101 — many common A/B/D signal/data codings.3
  • IEC 61076-2-109 — X- (and H-) coded high-speed data.4
  • IEC 61076-2-111 — power codings such as S/T/K/L.5

The two mix-ups this sheet exists to prevent​

  • A-coded current: many A-coded M12 connectors are in the ~4 A class within common standard/catalog scopes,3 but the exact rating depends on the connector, cable assembly, wire gauge, loaded contacts, and temperature. Use L-, T-, or other power codings where the exact datasheet supports the load.
  • D vs. X: D-coded is not obsolete — it is the common 10/100BASE-TX choice.3 X-coded is for GbE/10G-class Ethernet4 and is not a blanket default for every Ethernet use. Choose by data rate, then verify cable category, shielding, pinout, and assembly rating.

Record before you commit​

  • Coding and pin count, from the drawing (not the listing photo)
  • Standard identifier and edition/date checked
  • Manufacturer datasheet revision used for the design
  • Exact current/voltage rating for the loaded configuration
  • Gender, shielding, sealing (mated and unmated), and coupling torque per the exact datasheet
note

This is a working reference, not a standard. The datasheet, applicable standard, and customer/program requirements always win. Scenario walkthroughs: Industrial sensor · Rugged Ethernet.

Sources​

Footnotes​

  1. binder, M12 L-coded and M12 T-coded product families (screw locking per DIN EN 61076-2-111) — "L-coded versions have 4+FE contacts" with a rated current of 12 A/16 A at 63 V DC; "T-coded versions have 4 contacts with a rated current of 12 A at 63 VDC." Vendor example configurations, not universal M12 ratings — verify the exact datasheet. L-coded: https://www.binder-usa.com/us-en/products/automation-technology-voltage-and-power-supply/m12-l — T-coded: https://www.binder-usa.com/us-en/products/automation-technology-voltage-and-power-supply/m12-t ↩ ↩2

  2. binder, M12 K-coded product family — "K-coded connectors with screw locking according to DIN EN 61076-2-111 are designed for AC applications and have 4+PE contacts" (630 V class; vendor current ratings vary, e.g. 12 A — verify the datasheet). https://www.binder-usa.com/us-en/products/automation-technology-voltage-and-power-supply/m12-k ↩

  3. IEC 61076-2-101, Connectors for electronic equipment — Product requirements — Part 2-101: Circular connectors — Detail specification for M12 connectors with screw-locking (A/B/D coding): 2- to 17-way; data transmission up to 100 MHz; signal and power up to 250 V and up to 4 A per contact. https://webstore.iec.ch/en/publication/77773 ↩ ↩2 ↩3

  4. IEC 61076-2-109, … Part 2-109: Circular connectors — Detail specification for connectors with M12 × 1 screw-locking, for data transmission frequencies up to 500 MHz — covers the X- and H-coded variants; X-coding supports Cat 6A / up to 10 Gbit/s at IP65/IP67. https://webstore.iec.ch/en/publication/4425 ↩ ↩2

  5. IEC 61076-2-111:2025, Connectors for electrical and electronic equipment — Product requirements — Part 2-111: Circular connectors — Detail specification for power connectors with M12 screw-locking — per the current edition's abstract: 4- to 6-way connectors "with current ratings 8, 12 or 16 A per contact and voltage ratings of 50 V AC / 60 V or 630 V according to their coding." Treat these as edition- and configuration-specific scope figures, not universal M12 power ratings. https://webstore.iec.ch/en/publication/89862 ↩