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Substituting the terms “master” and “slave”

Many standardization bodies and industry consortia have started to adapt inclusive language in their standards, specifications, and other deliveries. Especially, “master” and “slave” are subjects to be substituted.

Standardization bodies such as IEC and ISO as well as industry consortia adopt increasingly inclusive language (Source: Adobe Stock)

Since a long time, the terms “master” and “slave” have been used in network technologies. However, the so-called political correctness has reached engineering terminology. This means, the mentioned non-inclusive terms are not appropriate anymore. Especially, in North America the demand to substitute them is high. Unfortunately, these terms have been used to describe different behavior, when they are used in combination with other words. If these compounds are substituted by new terms, they should reflect the technical method better than the not appropriate ones.

CAN in Automation (CiA) and SAE agreed last year, to substitute “LIN master” and LIN slave” by “LIN commander” respectively “LIN responder”. This is also appropriate for CAN FD Light: The responder nodes do not take the initiative to communicate, they only respond, when the commander node requests a communication service.

This looks different on the CAN-based Devicenet application layer. Sometimes, Devicenet “slaves” communicate without the Devicenet “master”. Therefore, the ODVA association developing and maintaining the Devicenet specifications decided to use in the future the terms Devicenet “controller” and Devicenet “device”. With the goal of eliminating terminology that is hurtful, these changes are the first in a series to update the entire library of ODVA specifications and documents to rectify the use of these terms.

“ODVA strives to be on the cutting edge of open, interoperable information and communication technologies in industrial and process automation,” said Dr. Al Beydoun, President and Executive Director of ODVA. “ODVA’s intentional movement towards inclusive and accurate language throughout its specifications is a positive step in ensuring that industrial automation is a first choice for all professionals.” As other organizations update terminology included in their publications, ODVA will update any normative references in the ODVA library of specifications.

In CANopen, the terms “master” and “slave” are used for different functions. For CANopen FD, CiA will use CANopen FD controller and CANopen FD device. “This represents best the functionality and behavior,” explained Holger Zeltwanger, CiA Managing Director. “For NMT (network management) and LSS (layer setting services), “producer” and “consumer” have been selected as inclusive terms, which describe these communication services very good.”

In CANopen, the term “CANopen master” has not been used in CiA specifications. Since mid of the 90ties, CiA 302 defines the “CANopen manager”, which implements the NMT producer and optionally the LSS producer. “CANopen device” is the new term for CANopen connectable units not producing the NMT message.


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CAN in Automation
Inclusive language CiA