question

@jan-kees

Yes (very unsupported) in theory with an mk3 to usb adaptor. It will be listed under devices very basic monitoring. And there will be no control using the GX. It is not designed to monitor two ve bus in erters unless configured in Parellel or 3 phase.

And you will see most likely see errors. Activate has dc system and consider a bmv so SOC will be a bit better.

Also is the bank big enough to support the second inverter as well as the first? Otherwise all you will be doing is punishing the most important part of the system.

There are better ways like using ac2 out of your current inverter if it is large enough.

there is a 24V 800AH house battery, with a BMV doing the 'normal' loads. The 2nd multi ( both 3000/24 ) will only service the induction plate. That way it can always be used as backup

so with the mk3 to usb adaptor I will see the 2nd multi on the gerbo or VRM?

I am just trying to view the energy use

Well....

I literally did this exact thing last weekend, only I shook it up even further and fed the AC in of the second 24V inverter from the ACOut of the 48V inverter.

Both Multi's

I can confirm that.

Plugging two multies into on GX, a CCGX in my case, will cause them to attempt to link up... Not possible with different devices even if I wanted to do that.

Connectingne of them via a MK-3 works, in fact it supports control from the CCGX, control and monitoring from VRM and even remote configuration,

Most of which I have seen multiple folk saying wouldnt be available.

HOWEVER... and its a big however.

I just discovered that when my BYD BMS shuts down the 48, which is considdered a 'system' state, it also shuts down the 24.

I turned off battery SOC monitoring for both the 24 and 48 which made no difference and neither was set to shut down on SOC anyway.

Now I am not sure this explanation is correct, it is based on what info shows up where, when looking at the Modbus System device registers and the fact that when the 24 shuts down it tells me that the BMS did it...

It dosnt have a BMS, at least not one it can talk to.

You also see conflicting information... My smart shunt reports the 24V bat SOC correctly, the 24V Multi will do the same, untill it gets shut off by the 'System' BMS. When that happens it reports an accurate voltage, way above minimum and then turns off anyway whilst displaying the SOC from the 48.

I want a well configured system with as much protection as I can get so will be buying another GX.

I am not 100% sure but I think if you were not using a system wide device reporting SOC it would probably be OK but then why would you want to do that.

I am not recomending anything here and I am no expert...
I am dealing with your exact scinario right now, device wise if not electrically.
What I am reporting is what I have found over the last week, determined the cause and effect, if not the mechanisme, by experimentation.

I thought this might work, I was wrong, as was advice saying it would be OK but limited. It is actually great, right up untill th BMS sticks its ore in.
Should have known better.

BTW...
I am using Node Red to read write Modbus, giving me an overview of the whol thing as well as determining how it should be behaving.
Charge current is not writable remotely but can be set with a physical input.
I was planning to use GPIO on the PI to drive that, off low, medium,high, using two relays and a few diodes but as I now have to by another GX I will use the relays on that.

Hope that helps, sorry it was a bit long...
[Please do not assume anything I am doing is even correct, let alone supported]