question

juergen pflug avatar image
juergen pflug asked

VenusGX ModBus TCP register addresses correct?

Hi.

I am trying to interface the VenusGX via Modbus TCP.


I have downloaded the CCGX-Modbus-TCP-register-list.xlsx as provided via the download link by email from Victron.

Date downloaded: 2019-08-25

According to the excel table "Document versions" it is: "Rev 23"


I have then tried to connect to the VenusGX using ModbusView 1.61 from Ocean Controls.


After some frustrating time playing around I get first results!

But I have a problem with the provided addresses in the excel sheet.


For example "Serial(System) address should be: "800"

but I have to use address "801" in ModbusView to get the expected result!


Is that something that ModbusView does wrong or is the address table wrong?

...or what am I missing here?


Thanks for helping

Modbus TCP
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4 Answers
juergen pflug avatar image
juergen pflug answered ·

I forgot, Venus GX Firmware version = v2.33

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Rob Howdle avatar image
Rob Howdle answered ·

Hi Juergen,


You will probably find this a lot when using Modbus. Typically, Modbus numbers its address registers starting at 1 (so the bits in a 16-bit integer would be 1-16). Most other (PLC) type equipment, would usually number from 0 (so bits 0-15 in the previous example). So you basically need to apply an offset (n + 1) whae addressing integers and bits!

Hope this helps.

Rob

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juergen pflug avatar image
juergen pflug answered ·

Just an update...
I am now using QModMaster which is free and without limitations!!
You can get it from here:

http://sourceforge.net/projects/qmodmaster

Since then, all port numbers seem to be correctly assigned.

and I managed to read out all my attached devices via the Venus GX ( Smart MPPT & Quattro inverter)

Best regards

Jürgen

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juergen pflug avatar image
juergen pflug answered ·

Just an update:

I am now using QModMaster and the ports number all seem to be correct. ( No + 1 needed )

QModMaster is free and has NO limitations!

You can download it from here:
http://sourceforge.net/projects/qmodmaster

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Related Resources

Modbus TCP Basics