Need help with reading data via Modbus TCP

Modifications
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1

Hello, I’m trying to read data through Modbus TCP from Cerbo, but I get big difference from what I see in Modbus responses and in Victron application.

I’m following registers:

  • sum of 820, 821 and 822 to get import/export from/to grid (in excel marked as Grid L1, Grid L2, Grid L3).
  • 817, 818 and 819 to get the whole consumption of house (marked AC consumption L1, AC consumption L2, AC consumption L3).
  • 842 for power from/to battery (marked Batter Power (System))
  • sum of 792 and 3730 from solarcharger section (marked as PV power, both)

I see the biggest difference in the power from battery and the overall consumption of house. Am I missing something?

2

Hello and welcome :waving_hand:

What sort of hardware do you use to read the registers?

3

Hello Steffen, I’m using Loxone Miniserver to read the data from Victron over network. On Victron side I am reading the data from Cerbo GX ‘system’ (grid, consuption, battery) and ‘solarcharger’ (PV power).

4

Check whether Luxone’s Modbus registers start at 0 or 1 … otherwise your registers will always shift by +1 … at least that’s how it works with Siemens Logo …

5

I don’t think it is the problem - for example all grid registers show ~the same value, which shows balanced phases. If It was register offset, one of the values would be significantly different given the registers around it.

The difference I’m observing seems to be me missing some register, I’m missing few kW for battery power and total consumption

6

Is the firmware on the GX up to date?
What sort of meter are you using to measure the readings?
Are you also using the correct Modbus address provided by the GX… Modbus TCP Server / available services…

How many times per second does the Luxone system query the registers?

7

Firmware is up to date AFAIK. Sort of meter should not matter - what I’m struggling to achieve is to get the same value I see over an app also over Modbus TCP, there is just one meter for both outputs.

I’m also using correct address, for example battery SOC provides same data for both.

Loxone queries every 5 seconds, but the difference is few kW with no change to consumption nor to weather

8

Why don’t you write a quick note about your system setup… It seems to be a three-phase system… what other components are installed that might need to be taken into account…
I reckon, though, that it’s the wrong register… as you don’t seem to be using a grid meter …
5 seconds is fine… I read the values 10 times a second, which works… I thought you were reading the values even faster, or even continuously.