The M12 Evolves—Will it Become the Industrial Automation Standard?
By Terry Harmon, Omron Electronic Components LLC

Industrial automation plays an increasingly important role in the global economy. Not only does this automation improve productivity costs, it also improves the quality of the products produced. Properly maintained, these machines do not tire, have off days, or take vacations. They are capable of precisely manufacturing the most demanding products with repeatability that cannot be matched by humans. This automation continues to become more and more complex with the likes of multiple robots, sensors, vision systems, radio-frequency identification (RFID), and programmable logic controllers (PLCs) being added.

The M12 style of connector has proven to be a workhorse in the industrial automation industry.

Prior to 1988, manufacturing plants relied heavily on parallel wiring to connect instruments and equipment. But this mode was inadequate for the needs of the ever-growing complexity of automated industrial systems. By the early 1990s, Fieldbus was emerging as the preferred industrial network system for real-time distributed control. Within the control chain, the Fieldbus links PLCs to the components which perform the work on an assembly line. These components include sensors, actuators, electric motors, console lights, switches, valves, and contactors. The standardization of Fieldbus protocols by Europe and the United States resulted in a demand for an environmentally-resistant connection between the PLCs and the industrial components. The M12 standard (IEC61076-2-101) was adopted to ensure proper connection to industrial components and to protect the interconnection from foreign particulates, dust, water, and hazardous substances. The M12 was chosen for its ease of use and reliability and soon caught the eye of the automotive industry, a major driving force in industrial automation. The primary hook-up method is by screw connection, which has become an industry standard among suppliers.

Initially, M12 connectors were tightly bound to automobile manufacturers, but they have since made inroads into other industries, such as machinery and tooling, packaging, factory automation, and food and beverage. As the number of applications grew, so did the variations of the M12. IEC61076-2-101 spelled out different types of "coding" needed to ensure proper connection within specific applications. For example, A-coding was established for general sensor connections (primarily in Europe), B-coding was set up for sensor connections (including AC sensors) for PROFI-BUS Fieldbus protocols, C-coding for sensor connections in North America, D-coding for Industrial Ethernets, and P-coding for a variety of other uses.

The IEC61076-2-101 (M12 style) connector coding system.

The Call for Improvements to the M12
As much as the industrial automation industry embraced the M12, there were some design drawbacks; as the number of uses grew, so did the request for improvements to the connector’s design. Concerns arose regarding the number of man-hours required to screw each and every M12 connector within a plant. There was also a lack of proper indication to the operator that the connection had been properly made. Operators also found it difficult to properly control the torque during hook up. There were even some instances where machine vibration was enough to loosen the connectors, requiring intermittent stoppages to fix the problem. The challenge for vendors became the need to address these issues while maintaining full compatibility with the M12 standard.

Next Generation M12-Style Connectors
In response to market demands, connector manufacturers have responded with the development of an M12 utilizing modified screw lock and bayonet locking mechanisms. The new lock designs add security and reliability, even in environments where heavy vibrations can loosen other connection styles. Improving on these locking designs, vendors have developed connectors that meet the requirements users were demanding.

This cut-away illustration explains how the “SmartClick” from Omron Components LLC works.
This connector is waterproof and carries an IP67 (Ingress Protection) rating and
can be applied in an ambient temperature range of -55 to 105°C.

 
A look at M12 connector suppliers.

Lower Application Cost:
Design improvements reduce installer fatigue caused by multiple terminations. Another time saver is in blind-mating applications where the installer must awkwardly reach to make a connection. With the new M12s, the connection is quickly and securely made.

Increased Reliability:
Under-tightened connections can cause intermittent signals in applications where vibration is present. Under-tightened connections can also lead to poor sealing. An over-tightened connection can damage the

O-ring, which can lead to poor sealing. Poor sealing would allow dust, oil, moisture, or other things found in the industrial environment to penetrate the connection and lead to an intermittent signal condition.

Backwards Compatibility:
What about all of the existing connectors already in applications in the market? Most new designs will mate with existing thread-style M12 connectors—they would be applied by screwing them on. This backwards compatibility eliminates the need to stock multiple styles. Vibration-proof options are available and are compatible with other M12 plug and socket models.

Reduced Downtime:
Estimates run in the thousands of dollars per hour of downtime. Not only are employees standing idle, but there is production lost from the equipment downtime. The advantages reviewed above eliminate the connection as being the source of trouble.

For years the industrial automation market has been asking for improvement in the M12 style connectors. New locking mechanisms provide a vast improvement over simple threaded connectors. As more industries embrace the IEC61076-2-101 standard, the variety of M12-style connectors will continue to increase. Vendors are already supplying junction boxes, Y-joints, and male/female sockets and plugs. As more uses are discovered, vendors will be continually challenged to offer more options to meet the growing demand.