I am adding a US3000C to an existing single US3000, which worked fine.
The existing system was connected with a CAN Type B wire. The US3000C needs a CAN Type A wire. I made an adapter, which I added to the Type B wire with a 1-to-1 LAN connector. I have tested the Type B wire and the adapted Type A wire with a LAN tester, and they are OK.
Because it didn't work, I disconnected the second battery (US3000) so that only the US3000C was connected, but not recognised.
As a check, I disconnected the US3000C and connected just the old US3000,which was recognised. I connected the CAN (type B) cable via the 1-to-1 LAN adapter and a 1-to-1 LAN cable, and it still was recognised. What I'm saying is, I don't think there is a fault in the CAN cable.
I updated the Cerbo GX firmware to the latest version (2.84) but still not recognised.