Why won't my Victron MPPT RS show up on the Cerbo GX over VE.Can?

VE.Can is a CAN-bus network, and a CAN bus that is not terminated at both ends may appear to work for a while and then drop devices, or never show them at all. That is the failure most people are looking at when a brand-new MPPT RS is cabled to a Cerbo GX and the device list stays empty. Work through the three checks in order.

1. Count the terminators

Victron's instruction is direct: terminate the VE.Can network at both ends using VE.Can terminators. In a two-device system the "ends" are the MPPT RS and the Cerbo GX, so one blue RJ45 terminator goes in the spare VE.Can socket on each unit. A bag with two terminators ships in the box with every VE.Can product, so check the MPPT RS packaging before you order any. Extra terminators are sold separately under part number ASS030700000; we do not stock them on their own, because every VE.Can product we sell arrives with its pair.

2. Check which socket the cable is in

The Cerbo GX has two independent CAN-bus interfaces, each with two RJ45 sockets, and it also has VE.Bus sockets that take the same RJ45 plug. The plug fits either. It is only correct in a VE.Can socket. If the cable landed in a VE.Bus port, the RS will never appear, and if a terminator went into a VE.Bus port it needs to come out: Victron says explicitly not to insert VE.Can terminators into VE.Bus ports. Note that "independent" means a device on one CAN interface is invisible to the other, so if you later add a CAN-bus BMS on the second interface, keep the RS on the first.

Use standard RJ45 UTP network cable. There is nothing special about the cable itself.

3. Confirm the RS is powered

All VE.Can devices supply power to the network, but a device only does that when it is running. The MPPT RS needs its battery connection made and the unit switched on. PV alone on a unit with no battery connected is not enough. Check the RS display shows it is alive before you go hunting for network faults.

If it still does not appear

• Update firmware. Connect to the MPPT RS in VictronConnect over Bluetooth and apply any pending update, then reboot the Cerbo and look again under Settings, then Device list.
• Swap the cable for a known-good RJ45 patch lead.
• Use VE.Direct instead. Within the RS family the Inverter RS and Multi RS cannot reach a GX device over VE.Direct, but the MPPT RS can. If you have a spare VE.Direct port on the Cerbo, a VE.Direct cable is a valid connection and a useful way to prove the RS itself is fine.

What to have on hand

The Cerbo GX MK2 has its RJ45 sockets rotated relative to the original Cerbo to make cables easier to remove in a tight bay. A spare RJ45 UTP cable is worth carrying with any VE.Can system. Everything ships from Upland, California, and if you send us the list of Victron devices in your build we will tell you which network each one belongs on before you order.