Hi all,
I got it. There is a small correction required in the Passing Serial over DroneCAN — Copter documentation (ardupilot.org), “Start the DroneCAN GUI tool over MAVlink to the autopilot and click the local node ID checkmark” to be changed to “Start the DroneCAN GUI tool over SLCAN to the autopilot and click the local node ID checkmark”.
After this, I’m getting the required node IDs.