I would like to commission another MultiPlus in my system. An MP1 is already running with Venus GX without any problems.
However, I am slowly running out of ideas with the new one.
What I want to do: control the ESS using a Siemens S7-1200 CPU.
The MultiPlus is configured in VE Configure:
-Germany: VDE-AR-N 4105:2018-11], internal NS protection
-ESS – also configured
Modbus was enabled in the GX, and the connection to the PLC was established (ID100 – (4)2701). In the ESS section, the setpoint I send from the PLC is displayed. Both positive and negative values are shown in the Remote Console.
The BMS inputs for charging and discharging are also received and displayed correctly in the menu.
Switch position on the device: “1”
If I enter a positive value in the PLC, the battery charges at the specified value.
If I enter a negative value in the PLC, nothing happens.
Does anyone have any idea where I could look?
I can provide all the information you need—just let me know what you require.
Connected to L1. However, I haven’t measured it at the grid connection point. It’s only one device anyway.
I’m using a Phoenix Contact meter, which I read via a PLC and to which I send the setpoint via Modbus.
That has worked the same way with my MultiPlus 1 since 2016.
I only changed the address on the PLC side.
So the meter itself isn’t connected to the MultiPlus.
The BMS is compatible; it only has the options to allow charging and discharging. It doesn’t have Modbus yet…
No meter has been found or configured.
Today, I compared all the values with those of the old and the new system (same battery). All VE Configure settings and all the settings in the Remote Console are identical.
The MP1 works with address 2700 and charges and discharges as it should.
The whole thing doesn’t work with the MP2.
I’m gradually starting to suspect that the MP2 needs more information from the battery. I can send it everything via Modbus—but what exactly?
Is there anyone here using a MultiPlus-II with external control? Which Modbus data do you send?
I’ve now managed to continue experimenting.
I’ve switched the communication to ESS Mode 3. I send the setpoints via value 37. The error remains the same.
It charges the battery, but it doesn’t discharge it there either.
There’s nothing displayed for Gridmeter…
I have the current Modbus TCP register table.
Edit: Problem not solved; cause & possible solution see next reply.
Good evening!
The problem is solved, although it is not exactly satisfactory and feels like a bug in Victron involving the two-signal BMS.
The cause was the ESS setting in VE Config. It only works with the Temperature and External 1 inputs when both are set to “closed”.
If you select anything else, they are displayed correctly in Venus (open/closed), but the MultiPlus does not respond. It feels as though an internal connection is missing.
I configured it, in effect, so that the MultiPlus would work without a BMS connected. In other words, with no cable connected and all signals showing as OK to it—and suddenly it worked.
I then closed the contacts. The Multi recognises them correctly and switches charging or discharging off.
(I also tried changing the contacts from closed to open in the config, but I always ended up with my original problem…)
The setting in the GX was not the cause. I even connected a Venus from my old Multi, but the problem remained… So that left only the ESS config…
@Matthias Lange - DE Indeed, that could be related.
But in that case, it’s a bug in Victron. You can configure it quite normally in the VE Configure software… the inputs are even shown in the interface. In the ESS configuration, you have to enter this separately… Really ridiculous…
Unfortunately, my problem hasn’t actually been fixed. I hadn’t tested enough.
I had an error today and my system no longer discharges the battery. When I checked, AUX1 was closed by the BMS (battery full). This prevents both discharging and charging. After bridging the contact, the MultiPlus was able to discharge. The page would indeed explain the error with discharging!
The temperature input works as intended and just as I know it from my old MultiPlus. When the contact is closed, the battery is empty and the Multi briefly charges the battery. So everything is fine here…
Unfortunately, when the battery is full, AUX1 causes the inverter to shut down completely. This means I can no longer get out of this situation.
Can I disable the ESS function for grid-supportive charging? Or can I simply use a different grid code?
Alternatively, is there a way to set the charging power at AUX2 from 4.2 kW to 0 kW?
Is there any other way to read an input from the Multi or the internally installed GX via Modbus? Then I could stop charging via a Modbus command.
Goal: the BMS stops the inverter from charging, but does not completely disable the inverter.
