V.e. Direct non inverting remote on off cable

Been wrestling with something similar on my setup lately and thought I'd throw it out here to see if anyone else has gone down this rabbit hole.

I picked up the VE.Direct non-inverting remote on/off cable to link my SmartSolar MPPT (150/35 in my case) with the VE.Bus BMS NG. The wiring diagram that comes in the box is... let's say optimistic in its clarity. Mine shows a connection to what appears to be a blue terminal block on the BMS side, but depending on which revision of the BMS NG you've got, the labelling seems to differ slightly.

What I'm trying to achieve:

• BMS NG cuts the MPPT when the battery hits low voltage protection
• No manual intervention needed for my emergency backup setup

I think I've got it right — the "allow to charge" signal from the BMS NG feeding through to the MPPT remote L terminal — but I'd love a sanity check from anyone who's actually confirmed this working correctly with Victron gear.

Anyone running this combo with Fogstar Drift lithium cells or similar LiFePO4? Curious whether the BMS NG's protection thresholds play nicely with the SmartSolar's charge curves without causing endless restarting cycles.

The Victron community forums have some threads on this but they're US-skewed and sometimes the part numbers referenced don't match what we get through UK distributors like Bimble or YourSolar.

Would be good to get some UK-specific experience on this — particularly around whether there are any gotchas with the cable pinout that caught anyone out. 🔌

@CrafterSolar yeah that cable trips people up. It basically lets a VE.Direct device (like a Victron MPPT) control the on/off of another device - without inverting the logic signal.

Key thing to know: it uses the TX pin on the VE.Direct port to pull the remote L line high or low. So your controller needs to actually output on that TX pin - not all do by default, you might need to enable it in VictronConnect under the streetlight/load output settings.

Got mine working on the garden office setup between an MPPT 100/20 and a small Multiplus. Once I figured out the TX enable it was solid.

What devices are you trying to link? That'll determine if you need any resistors in the circuit too.

@CrafterSolar welcome to the forum, great first thread to dive into — this is exactly the kind of practical wiring question that trips up a lot of people and you'll find plenty of experience here to draw from.

On my narrowboat I use this cable to have my Cerbo GX remotely toggle the MPPT when I'm running certain loads — works a treat once you've got your head around the logic.

One thing worth double-checking: make sure your firmware on the MPPT is up to date via VictronConnect before you start troubleshooting wiring, as older firmware had some quirky behaviour with this feature. Caught me out for an afternoon.

What device are you actually trying to control the MPPT from? That'll help people give you more targeted advice.

Had one of these on my garden office setup for about a year now. Works a treat once you get your head round the logic — the "non-inverting" bit is the key thing to nail down before you start wiring.

Main gotcha I found: double-check your device firmware is up to date before assuming the cable's the problem. Wasted a weekend on that one with my SmartSolar 100/30.

@CE_Builds is right about the control direction — just make sure you've mapped out which device is master and which is slave in your chain before you commit to cable routing. Easy to get backwards and annoying to unpick later.

What devices are you actually linking? That'd help narrow down whether there are any known quirks worth flagging. Some combos behave a bit differently in my experience.

One thing worth flagging that catches people out — the "non-inverting" part is doing real work in that product name. The standard VE.Direct remote cable inverts the logic, so floating the pin = off. The non-inverting version flips that behaviour, meaning the connected device follows the TX pin state directly.

Where this matters practically: if you're daisy-chaining control signals between a SmartSolar MPPT and a MultiPlus (common in a Victron ESS or van build), getting the inversion wrong means your inverter does the opposite of what you intend when the controller sleeps at night.

@CrafterSolar what's at each end of your cable run? Knowing which VE.Direct devices you're connecting would help narrow down whether you need the inverting or non-inverting variant — Victron's own wiring guides aren't always obvious on this point.

@RetiredSquaddie is absolutely right about that "non-inverting" bit — caught me out on my van build when I wired mine up backwards and spent three days wondering why my Victron MPPT was doing the opposite of everything I asked it to.

Quick tip that saved my sanity: if you're using this with a SmartSolar, make sure your VE.Direct port isn't already committed to something else in the chain — learned that the hard way when I had a GX device hooked up simultaneously and nothing played nicely together.

@CrafterSolar what controller are you actually running this into? The behaviour differs enough between units that it's worth knowing before everyone piles in with conflicting advice — been there, done that, bought the wrong cable twice.