CAN Application Layer & CANopen


CAL stands for “CAN Application Layer” and was originally developed by CAN in Automation (CiA). The CAN Application Layer is divided into several parts, for example:

  • CMS (CAN-based Message Specification) which defines protocols for transferring data between CAN modules
  • NMT (Network Management Service) which defines the protocols for system startup and shutdown, error logging, and more
  • DBT (Distributor Service) which defines a protocol for distributing identifiers to the different modules in a system

CAL is clearly influenced by the OSI model. CANopen is essentially a subset of CAL combined with a set of profiles, which are not yet finalized. CAL/CANopen is one of the currently four higher layer protocols supported by CiA. Both the CAL and the CANopen draft specifications are available from CiA.


Article: On the Difference Between CANOpen and CAN Kingdom

More information about CAN in Automation.

Watch the update on “CANopen FD”, presented by the CAN in Automation group.

More Resources