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Modbus TCP

Feature Request: Write access to Multi RS Solar ESS Settings

I would like to request the ability to control the following via NodeRed/Modbus for the Multi RS Solar:

1) ESS Mode (Optimized with batterylife, Optimized without battery life, Keep batteries charged)

2) ESS Minimum discharge SOC

Both would be useful but either would do.

Charging batteries during cheap times is possible but requires fudges to make it work. I can use Generator rules to turn on the input relays at night and also if I have a large load. The downside is I end up charging the batteries during the day if I have a large load.

I currently have to use a Windows PC to automate clicking buttons in the VictronConnect App to set the ESS Mode!

Don't know if there is a formal method for asking for features but please accept this as one :)

Please Help.......

semlohnhoj asked
semlohnhoj answered ·

1 Answer

Missing: Days until next automatic equalization info

As I explained elsewhere, I am very much missing the ability to see how many days are left to the next scheduled automatic equalization (SmartSolar MPPT 250/100 VE.Can).

This is critical info when you are running on lead acid batteries (as you need to check the electrolyte level).

It seems to me that this information - which was shown in my previous Solar Charger - ought to be part of VictronConnect.

Also, while dwealing on CCGX-Modbus-TCP-register-list-2.90.xlsx, I see this variable nowhere. Neither is it, apparently, part of Node Red, where one could for instance want to program the issuing of a warning the day prior to equalization.

hvalentim asked

0 Answers

disable discharging when car is charging


i'm new to Victron but long term smarthome user/DIY developer and know something about modbus. But i didn'nt understand some relationships of setting in my ESS System.

I have 3 Multiplus2, Pylontech Battery and CerboGX running large image.

ESS mode is 1, Optimized mode or 'keep batteries charged' and phase compensation enabled

ESS State = 5, Optimized Mode /w BatteryLife: SoC below dynamic SoC limit



I want to disable discharge battery when my e-car is charged by an go-e Charger.

My idea was to set the related state through MQTT and the Victron Nodes.


But i was not able to figure out which are the right/best settings i have to change.

Is it ok to set just the ESS state to 9 - 'Keep batteries charged' mode is enabled?

karlschindler asked
tyr edited ·

3 Answers

Unstable Modbus/TCP connection to Multiplus 2 GX

I'm operating a Multiplus 2 GX with activated Modbus TCP (see Picture 1). A separate Raspberry Pi which is running Node-Red connects to the Modbus/TCP endpoint. The modbus TCP connection is used to read information from the Multiplus and to control the ESS based on my dynamic energy tariff. While the communication itself works quite well, the connection to the Multiplus is unstable and breaks regularly (see Picture 2). To be able to reconnect I have to move the the modbus connection in the editor slightly and re-deploy in Node-Red. I've tried to optimize the connection settings (see Picture 3) towards the Multiplus but without any impact.

From my current perspective there is no reason for the instability. Within the VRM portal there are no connection issued and the state of the Multiplus is reported without data gaps or connection issues.

Picture 1


Picture 2


Picture 3


sascha-brinkmann asked
sascha-brinkmann answered ·

2 Answers

How can I make "AC input 1 source type" writable via ModBus?

I'm running a setup in an RV with Home Assistant. I'd like to auto switch the "AC input 1 source type" depending if my generator is turned on or not to maximize battery charge behavior (yes, it does differ, battery charges to 100% with ESS when set to generator, maintains set percentage if shore or grid).

I don't mind forking the Venus OS if needed and submitting a PR if I can get some tips on where to start.

Edit: Looks like this is the line:

zorrobyte asked
zorrobyte answered ·

2 Answers

GPS modbus Lat & Lng

Trying to read gps Lat and Lng off of modbus which I believe should be on address 2800 and 2802 but the values appear wrong in Node-Red but correct on the Remote Console.

Correct Lng on Remote Console:-


Modbus node settings


Output in Node-Red


Can anyone help or explain what is wrong or I'm doing wrong?

Thanks for any help.

xsilvergs asked
Dirk-Jan Faber rolled back ·

5 Answers

NodeRed on Multiplus GX (Large) - Modbus Server Node (EM24 simulation) not visible

Hello, i have a working node-red flow which is simulating an EM24 over an modbus server. NodeRed is running on a seperate machine with Home Assistant and Node Red.

This is used for a Modbus Power Meter for the PV-Values. It is visible in Venus OS as an Modbus TCP Device

I want to run this flow on the integrated Node Red in the large version. The input of the values (Modbus-TCP and JSON) ist working, but not the Modbus server. I've tried different Modbus ID's and Ports with no sucess.

Is it possible to run it on the same machine (GX on Multiplus-II)?

parateam asked

0 Answers

Modbus Register for Relay 3,4,5&6 for Raspberry pi

Where might I find the Modbus registers for the Extra relays the Raspberry pi has? I have looked in the Excel Modbus-TCP register list, but can only find Relay 1 and 2.

I used the RpiGPioSetup add-on to assign the extra relays. I can see and control the extra relays using Remote Console.

I currently have NodeRed running on external device controlling Relay 1 and 2. I am looking to control the other relays (3-6). NodeRed is also pulling data from my BMV-712 / other Victron items.

mrorange asked

0 Answers

Ignore AC input over modbus / dbus?

I am looking for a way to just ignore the AC input.

I have modbus tcp and access to the dbus thru nodered, but I dont see how i would change that setting.

Currenlty i overwrite the settings manually every day with VEConfigure, but that is pretty painfull. :)

How can I achieve this and make some nice flows in nodered?

betz asked
jacola answered ·

3 Answers

VenusGX + Node-RED - Modbus TCP Communication Issues


I have installed the recent VenusGX v2.42 FW build with integrated Node-RED from

I am trying to communicate with an external device via Modbus TCP (a My PV AC Thor - which is a modulated AC heater power control unit) and control it via logic developed within Node-RED.

I have successfully installed the additional contrib node 'node-red-contrib-modbustcp' and am able to communicate with the unit.

However I'm unable to setup a flow to BOTH write to the unit (with a power request) at regular intervals AND read from any registers (such as temperature) at regular intervals.

For example;

Write only - connects/works fine


Write & Read - no connection



Write & Read after a few minutes - write connects/works but read doesn't


Read only (write node deleted) - connects/works fine


I do know that a Modbus TCP read and write event can't occur exactly simultaneously (and it doesn't need to), but I'm not sure how to sequence the read/write requests or what I can change to get this working with the Modbus TCP node-set that I'm currently using...

My next step was to attempt installing a different / mode advanced Modbus contrib node 'node-red-contrib-modbus' (I have seen examples of write and read nodes successfully coexisting with this node-set) but unfortunately I get a bunch of installation errors - see below;


I have also tried to install manually via Putty using the npm install command (including the suggested variations) but still get the similar errors.


My programming/Linux skills are very limited, so troubleshooting this myself is a bit beyond me.

If anyone is able to offer some advice on how I can possibly get write and read communication working with the current Modbus node-set I'm using ( or how to get the more advanced Modbus node-set ( successfully installed on the VenusGX it would be greatly appreciated.

PS. I do know that my other option is to run node-red externally to the VenusGX unit (such as on a RPi), but I want to leave this as a last option for now.

Thanks in advance, Mark.

Mark asked
shaun commented ·

1 Answer

Get data from my Victron Venus to my Node-Red ...

Hi all,

I would really like to get any kind of data from my Venus GX into my RPi Node-Red Installation.

What I tried so far:

Modbus ... unfortunately it is not possible to read data from Node-Red using the Modbus Nodes like that:



Although the reference guide tells me: Address 800 - length 6 --> Serial number

Second I tried to use the existing Victron Nodes - I added the Environment line as explained in the instructions:

  1. Environment="NODE_RED_DBUS_ADDRESS="

But still the Victron-Nodes are empty ... no connection to my Venus seem to be possible:



and thats a pitty, because I really would like to see at least ANYTHING :( :( :(

Please help me ...



gawan asked

0 Answers

Controlling TriStar diversion controller over Modbus


I'm planning my off-grid system. The main issue I have is the AC coupled wind inverter which doesn't support frequency shifting.


In order to protect the batteries from overcharging my plan is to use Morningstar Tristar PWM in diversion mode.

Unfortunately it doesn't support communication with BYD's BMU. I hope it's possible to use Modbus communication and send to it charging parameters from the Venus OS (node-red).

It will allow TriStar to dynamically divert excess power and keep the batteries happy ;)

Do you think it's possible?

Thanks for your help ;)

dyju711 asked
dyju711 answered ·

1 Answer

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