What does the coding mean on M12 connectors?

M12 connectors are circular connectors with a 12-mm locking thread used for sensors, actuators, Fieldbus and industrial Ethernet, primarily in factory automation applications. Often with ratings ofIP65, IP68 and IP69K, they are ideal for washdown and corrosive environments.

They are available with 3, 4, 5, 8 and 12 pins. While higher pin counts are not planned, other locking styles such as bayonet and push-pull are continuously under development.

The M12 family can be found in many applications such as factory automation, measurement and control, communications, food and beverage, transportation, agriculture, robotics and alternative energy.

When it comes to specific applications, users must select the right pin count. For sensors and power applications, 3 and 4 pins are required. Profinet and Ethernet use 4 and 8 pin counts. And Fieldbus, CANbus and DeviceNet primarily use 4 and 5 pin counts. Finally, specify 12 pins for signal requirements.

Several styles of coding exist in M12 connectors. This coding prevents incorrect mating on products. In addition, shielding is available in most coded M12 connectors. For example, X-coded connectors are specifically shielded by the design of their coding.

The most common types of coding include:

• A-coded for sensors, dc power and 1 Gbit Ethernet
• B-coded for Profibus
• C-coded for ac power
• D-coded for 100 Mbit Ethernet
• X-coded for 10 Gbit Ethernet
• S-coded for ac power (will eventually replace C-coded power parts)
• T-coded for dc power (will eventually replace A-coded power parts)

A-, B-, D- and X-coded are most prevalent. This is because the A-, B- and D-coded connectors have been around for a long time and are some of the original M12 connectors. X-coded connectors are becoming more popular for high-speed industrial Ethernet and will eventually replace the A and D-coded parts for Ethernet applications.

A new code, K-coded, is under development for ac power, while a L-coded design will be released soon for Profinet dc power.

Special thanks to Binder USA for assistance with this article.