Most DEB links operate on a bus topology. Ensure the last device in the chain has a physical or software-toggled terminator to prevent signal bounce-back.
Solution: Refresh the bus scan in the software. If they still don't appear, verify that no two modules share the same hardware ID. ncontrol deb link
Manually set the ID switches (often DIP switches) on each expansion module before powering up the link to avoid address conflicts. Troubleshooting Common DEB Link Issues Problem: The DEB Link LED is flashing red. Most DEB links operate on a bus topology