Nucleo GX AC Input1 & AC Input2 unknown

Had a similar head-scratcher when I was commissioning the setup in my shepherd's hut last spring.

I'm running a Victron Multi RS paired with a Nucleo GX, and when I first powered everything up, the AC input monitoring was showing as unknown across both Input 1 and Input 2. Spent the better part of an afternoon convinced I'd wired something daft.

Turns out the Nucleo GX seems to take its time "discovering" what's actually connected — especially if you've got a third-party AC source on one of the inputs. In my case it was a small Honda generator on Input 2. The unit eventually sorted itself out after a full power cycle and letting VictronConnect finish its initial sync, but it wasn't obvious at all that this was just a waiting game.

What I'm curious about is whether anyone's had this with a SolarEdge or similar grid-tie inverter on the AC input side. I imagine the handshake between the Nucleo and a PV inverter that's doing its own frequency/voltage dance could get a bit confused.

A few things worth checking if you're stuck:

• Is your DVCC configured correctly for the Multi RS specifically?
• Check the AC Input source settings in the Remote Console — sometimes these default to Not Available after a firmware update
• A hard reboot of the Nucleo (not just standby) cleared mine

Anyone else migrated from a Cerbo GX to the Nucleo and hit weirdness during the transition? Feels like the Nucleo is still a fairly young bit of kit and the community knowledge around edge cases is thin. Would be good to pool what we know.

@GaryParker97 oh this rings a bell from when I was setting up my narrowboat system! Quick question though — did you check whether the Nucleo GX had actually detected the Multi RS via VE.Can or VE.Direct? I had a similar "unknown" status on my inputs and it turned out the device just hadn't fully handshaked yet after first boot.

Also worth double-checking: is your AC Input 1 configured correctly in the GX settings for shore power vs generator? I remember reading that if the input type isn't explicitly defined it can just show as unknown rather than erroring out properly.

Which firmware version are you running on the Nucleo? There were some known quirks with earlier releases that Victron sorted in later updates — might be worth checking the Victron Community forum for your specific build number.

@GaryParker97 oh the Nucleo GX loves to play dumb about AC inputs — it's basically the teenager of the GX device family. Sits there pretending it doesn't know what's plugged in whilst quietly judging your wiring decisions.

Nine times out of ten with a Multi RS this comes down to the AC input configuration not being set correctly

@GaryParker97 this caught me out too during my motorhome build. The Nucleo GX won't show AC Input 1 or 2 properly until you've told it what those inputs actually are in the device settings — it doesn't auto-detect.

Go into Settings → System Setup → AC Input 1 and set it to "Grid" or "Generator" as appropriate. Same for Input 2. Without that, the GX just shrugs and reports "unknown" because it genuinely doesn't know what's connected.

The Multi RS also needs its VE.Can configuration to be solid — worth double-checking there are no address conflicts on the bus if you've got other devices on there. A quick VRM portal check will tell you if the GX is actually seeing the Multi properly versus just partially handshaking with it.

Had this exact nonsense with my motorhome setup. Worth checking your VE.Bus cable first — if it's even slightly dodgy or the wrong length, the Nucleo just sits there reporting unknown on both AC inputs like it hasn't got a clue.

Also double-check the Multi RS firmware. Had mine on an older version and the GX couldn't interpret the AC input status properly. Updated via VictronConnect and suddenly everything made sense.

@CaddyCamper is on the right track I think — but I'd add that the input current limits in the assistant settings can sometimes confuse things too if they're set to zero or left at defaults. VEConfigure is your friend here, painful as it is to use.

What firmware version are you running on the Multi RS?

Double-check your AC input source is actually live when you're looking at the Nucleo GX display — it'll show "unknown" all day long if there's nothing feeding it to detect. Also make sure you've assigned the correct input type (grid/generator/shore) in the Nucleo's settings under System Setup, because it won't guess for you. @OffGridMax is right about the VE.Bus cable but I'd also verify the Multi RS firmware is current — had my narrowboat setup throwing similar nonsense until I updated via VictronConnect and suddenly it all made sense.