Process data object (PDO) mapping is an essential feature of CANopen that describes which individual process variables in the data field of a PDO is transmitted. CiA 301, in particular, requires a dedicated re-mapping procedure.
CANopen features mandatory, conditional, and optional parameters. However, the device still has to behave as specified even if the optional parameters aren’t implemented to ensure interoperability.
There are some misunderstandings regarding the multi-master functionality of CANopen-based control systems. The under-laying CAN data link layer is a multi-master protocol, and each CAN node has the right to request bus access at any time. Depending on the priority of the CAN data frame, the node gets immediate bus access or it has to wait.
Compatibility is just a marketing term. Testing of conformity is nice to have, but customers are more interested in interoperability. With CAN controllers, different test plan implementations can lead to different results. CiA and other consortia organize so-called plug-fests, where prototypes and just released devices are tested on interoperability.
Standards might be boring to read about, but we couldn’t do without them. Without standards modern civilization would be much more difficult, costly, and hazardous, because we didn’t standardize the fire hydrants.
The CiA 402 motion control and drives profile originally developed for CANopen systems will be extended for functional safety. In addition, A new PDO mapping was introduced, to control asynchronous as well as synchronous motor with the very same device.