Many drives, battery systems and CAN interfaces use RJ45 sockets so devices can be daisy-chained with ordinary patch cables. CiA recommends one pinout — but not every vendor follows it, which is the source of many “why won’t my battery talk to my inverter” problems.
In the CiA layout pin 1 is CAN High and pin 2 CAN Low — a twisted pair in standard Cat5e/6 — with ground on 3 and 7, shield on 6 and supply on 8. Switch to the Victron VE.Can variant to see a common alternative.
Plug, contacts facing you, latch away — pin 1 on the left
| Pin | Signal |
|---|---|
| 1 | CAN High |
| 2 | CAN Low |
| 3 | CAN ground |
| 4 | Reserved |
| 5 | Reserved |
| 6 | CAN shield — Optional |
| 7 | CAN ground — Optional, same as 3 |
| 8 | CAN_V+ supply — Optional |
| Recommendation | CiA 303-1, now CiA 106 |
|---|---|
| CAN pair | 1 High, 2 Low (one twisted pair in T568A/B cable) |
| Other pins | 3 and 7 ground, 6 shield (optional), 8 supply (optional), 4/5 reserved |
| Cable | Straight-through Cat5e/6 works physically |
| Pin 1 | Plug with contacts facing you and latch away: pin 1 on the left |
CiA specified the RJ45 assignment alongside the D-sub and M12 in its CANopen connector recommendation (CiA 303-1), now consolidated in CiA 106. It caught on wherever cheap pre-made patch cables and daisy-chained devices make life easier: building automation, drives, and solar and battery systems.
Choose any two connectors to get a pin-to-pin wiring diagram, with wire colours, which pins to leave unconnected, and the power and termination warnings that matter. Hover a wire to trace it.
Pick two connectors to draw the wiring. (Needs JavaScript.)
Following CiA: pin 1 CAN High, 2 CAN Low, 3 ground, 7 ground, 6 shield (optional), 8 supply (optional), 4 and 5 reserved.
Yes — a straight-through Cat5e or Cat6 patch cable works, and pins 1 and 2 form a twisted pair. Never connect a CAN port to Ethernet or PoE equipment.
Vendors use different RJ45 CAN pinouts — Victron puts CAN on pins 7 and 8, CiA on 1 and 2. Check both sides and use a matching or custom cable.
Hold the plug with the contacts facing you and the latch away from you: pin 1 is on the left.
Sources: HMS / Ixxat CAN connector pin reference; CiA 106 connector pin assignment; ICC: locating position 1 on RJ45; Victron: VE.Can RJ45 BMS cable.
Last reviewed 2026-10-27. Pin assignments follow CiA 303-1 / CiA 106; OEM variants are noted where we could verify them. Spotted an error? Tell us.
iMatrix designs and builds CAN, J1939 and OBD-II harnesses for OEMs and fleets, and our FleetConnect telematics devices plug straight into the 9-pin and OBD-II ports. Tell us the two ends and the quantity.
