mikeseaman3000 avatar image
mikeseaman3000 asked

Modbus TCP & Control of Cerbo GX/Quattro

Hi Everyone,

I need a little help with Modbus Control. I have a Cerbo gx and quattro unit with pylontech batteries. It is all working perfectly however i am looking to interface to my home automation system.

Does anyone have experience with Modbus TCP registers on here?

I am looking to enable and disable charge plus also have the option to maximise the output of the inverter so that I am able to to discharge to grid where possible. Any help with some configurations of the Modbus.

So basically any help with modbus config is great. I have got the communication working perfectly and able to read values from the cerbo gx, i.e. SOC of batteries. via modbus.

Appreciate any help.



MultiPlus Quattro Inverter Chargercerbo gxModbus TCP
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nickdb avatar image nickdb ♦ commented ·

Have you downloaded the list of registers? It details which are writeable and which not.

First place to start is to see if what you want to set can be set.

I want to change the ESS inverter limit by time of day and weather, unfortunately this register does not exist as far as I can see so that pretty much torpedos my automation plans.

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mikeseaman3000 avatar image mikeseaman3000 nickdb ♦ commented ·


Thanks for the reply. Yeah i managed to download the registers, but i cannot seem to force the charge and discharge over Modbus. Any ideas?

Is there not a way to write to the grid setpioint for Inverter Limit. You can do a calc in your external controller that takes the consumption and limits what the inverter outputs?

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nickdb avatar image nickdb ♦ mikeseaman3000 commented ·

what home automation are you using?

I have been working with home assistant which seems to work fine.

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gnsa14 avatar image gnsa14 nickdb ♦ commented ·

Hi nickdb,

Can you tell me which registers you are using to control the charge / discharge limits? I am running ESS in mode 1 (maintaining 0 watts grid flow)
I have reviewed all the writable registers in the CCGX Modbus TCP register list v2.7 but cannot find any that will allow to control these two via HA.

What I am wanting is not to force the rate, only to limit the rate.

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2 Answers
lifeingalicia avatar image
lifeingalicia answered ·

I have not played with those but

should be register 2316 but it is current so it would be in amps or ESS registers 2701 2702 but these are in % 2704 which is named current but is in W

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mcflexus avatar image
mcflexus answered ·

Any update on this? I really want to do the same, in the correct way. If not possible would it be thru mqtt or node red? Modbus would be the nicest iption tho.

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