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How the M8 and M12
Connectors Became the
Backbone of Today’s
Industrial Automation
The year 2015 marks the 30th
anniversary of the M12 sealed
interconnect system. Over those
30 years, the M12 system has
established itself as the go-to
option for harsh environments that
need reliable, hardened solutions
for connectivity. Let’s take a look
back at how the connectors were
developed, how they evolved, and
how it came to be the preferred
interconnect system in industrial
automation today.
The M12, and its smaller cousin, the
M8 connector, traces its lineage back
to 1982 when a Germany-based
company introduced the RK30 – a
7/8 inch circular, 3-pin, screw-type,
The 4-pin version allowed for more
advanced sensors and actuators
to be included in a single system.
Little did we know that this product
release would set the direction for
industrial automation connectivity
for the next three decades. The M8
would hit the market four years later
in 1989.
Following the introduction of the
M8, both the M8 and M12 became
standardized under IEC 61076-
2-101, which resulted in the two
connectors being nearly universally
adopted for industrial control
systems.
Applications for M8
and M12 Interconnect
Systems
The M8 and M12 have become
favorites for anyone in need of
Selecting and Implementing M8 and M12 Connectors
Tim Senkbeil, Belden company
“waterproof” connector. This pre-
assembled, overmolded connector
was rated to IP67, meaning it was
dust tight and remained watertight
even if temporarily submerged. Used
to connect industrial sensors, this
precursor to the M12 found its first
industrial automation application at
an automotive plant, a market that
remains key for the M12 connector
to this day. Prior to the M12, options
were limited: engineers were forced
to hard wire or constantly replace
connectors that could not withstand
harsh environments.
Three years later, the M12 connector
was introduced and stole the
spotlight of the Hanover Fair in 1985.
The M12, released with 3- and 4-pin
versions, used the smaller metric
M12 thread and had a smaller current
rating, but retained the IP67 rating.
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