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RUGGED COMPUTING · CONNECTORS

What Is an M12 B-Coded Connector?

An M12 B-coded connector is the M12 coding reserved for PROFIBUS fieldbus networks. It usually has 5 pins and a key in a different position from A coding, so a fieldbus cable cannot be connected to a sensor or power port by mistake.

01

The Short Answer

B coding exists to keep fieldbus separate. PROFIBUS devices on a machine sit alongside sensors that use A-coded M12, and the different key position means the two can never be swapped during installation or maintenance.

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    Pins Usually 5: two data lines, supply, ground and shield.
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    Network PROFIBUS DP and other RS-485-based fieldbuses.
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    Standard IEC 61076-2-101.
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    Cables Shielded twisted-pair fieldbus cable, with the data lines usually colored red and green.
02

B-Coded Connectors Today

Many plants now move from PROFIBUS to PROFINET, which uses D-coded or X-coded Ethernet instead. B-coded connectors remain common on existing lines and where fieldbus devices are extended or replaced. Our guide to M12 connectors compares every coding, and the M12 coding FAQ explains how coding works.