Welcome to Ars-Informatica  


If you want to build a ship don't herd people together to collect wood and don't assign them tasks and work, but rather teach them to long for the endless immensity of the sea. (Antoine-Marie-Roger de Saint-Exupéry)


There are 3 different kinds of "identifiers" within CANopen: the Node ID, the Object Dictionary Indexes, and the COB ID or CAN ID.

  • The Node ID is used to identify a specific CANopen node. The allowed range for Node IDs is from 1 to 127.
  • The Object Dictionary’s Index and Subindex (16-bit and 8-bit "identifier") are used to identify a specific variable (which can be process data or configuration data) within a node. The Object Dictionary is described here.
  • The COB ID is the "Connection Object ID" and primarily identifies a specific message on the network. This ID directly corresponds to the CAN message ID. In a CANopen system, a COB ID is unique and used for one specific communication channel (from one node to one or more other nodes). In addition, the COB ID may include control bits, such as an enable/disable bit.