Q: Can the node IDs in a CANopen® network be auto-assigned?

A: Although it is not part of the original standard there are several, application specific ID claiming implementations, including one suggested in one of the application profiles (door control). Depending on the application requirements, several options are available.

Pure software solutions usually require that each node has a "unique number of bytes", either in form of a serial number or a random number generator. Depending on bus speed and number of nodes, the claim-cycle may take several seconds to execute.

Other applications might require that the node ID is related to the physical location in the network. So if the node IDs should really be 1, 2, 3, ... sorted by their physical location, then additional hardware is required.

We have seen several implementations that use an additional wire in the cabling for this purpose. And there are several options on how to use this wire - one is creating a daisy-chain (going in and out of each node, with each node having the possibility to switch the signal for the next node in the chain). In this case the node "closest" to the master will be configured first. Once it is configured, it enables the next node in the chain.

Contact your favorite consultant for help with any of the methods above.