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Multiplus II GX ModbusTCP reading problems

Multiplus II GX connected to Liion Battery. ESS activated. Only AC-IN connected, no AC-Out

When ESS in "optimized" I can set the grid point with register 2700 on ID 100.

When setting ess to "external control" (aka Mode 3?) the Multiplus goes into ESS passthru.

On top of that ID 242 / 246 is not readable (registers 37/38/39).

They are also not readable in optimized mode and also tried reading them with ID 100. No chance.

I can write to them, but nothing happens.

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I have been looking at simmilar stuff recently because I want to manage my generator with a PLC and hook the entire system to a HA system I am working on.

I am off grid so no ESS in play and may battery is BYD so no relavent experience but I did note that when my kit is in 'external control' it is because the BYD is driving its parameters.

I cant help wondering if the lack of responce to a control register, that you are seeing, is because something else has, or should have, control at that point.

I found the documentation frustrating, not because things dont work but because I cant find how or why they do.

Case in point... Untill my battery got cold the other day I didnt know if the chrge current on the MPPT would get modified as per BYD spec. It did and the portal reported that but I couldnt see it locally! I suspect there is an internal register, that the BMS drives, that the MPPT uses when in external control.

I havent found a single document describing what is governed by what else, in a given configuration or circumstance. it works but generally I dont know why or how.

snaptec avatar image snaptec Alistair Warburton ·

Thanks for your opinion, Victron has really great stuff that can do almost everything. You need just to find out how to figure the setup out.

As there is other stuff hooked up to the battery I don't really want to use mode2 aka optimized.

Also didn't get the Multiplus out of "ESS Passthrough".

A link to a document what else need to be configured would be perfect.

Just found this:

linking to this:

All the options are disabled on "external control".

Some more infos that may help:

- Lithium is checked in VE.Configure

- Battery Monitor is set to internal, but at the moment always showing 100%

- connected is a 12s 640Ah Liion Battery with own BMS / Active Balancers and as I'm paranoid with own DC Relais for turning everything off.

- Other stuff connected to the Battery, that's why I would like to control it myself.


In Optimized mode the "Inverter AC output in use" is not shown.

The internal inverter is still on, but I don't need that. Is there a way to disable it for ongrid ESS?

1 Answer
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No one?

Victron says: " Talk to your dealer", Dealer says: "Handing that out to our techs", no reaction.

Multiplus mounted and not useable.

Feeling a bit lost, is my use case that exotic?

Side question:

Regarding the TCP Register, Register 301/302 (charged & discharged energy) is not readable.

Which modbusID to use?

Is it possible to get the charged & discharged energy from AC in?

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Got an answer from Victron itself.

In v2.34 it is not possible with the gx.

Upcoming in 2.4

Questions regarding register 301/302 are still uncleared.

I have Multiplus-II gx in ESS mode 3 running fine, but one thing appends before that the VEbus Id change from 242 to 228

I dont'nt know why but it's.