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Rabeendra Tilakaratne avatar image
Rabeendra Tilakaratne asked

Communication with Cerbo GX

I am using Siemens LOGO controller to control my Off-grid system controlling. Currently using hard wired system. I need to connect the Cerbo GX to LOGO controller through RS485 or Ethernet. Is it possible ? If so how can I get the addresses of Cerbo GX. I can see all the graphs on Victron Connect.

communication protocol
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2 Answers
Alex Pescaru avatar image
Alex Pescaru answered ·

Hi @Rabeendra Tilakaratne

From what I know, the Cerbo / Venus OS is quite a close/proprietary system, not so easily to integrate into an industrial environment.

It will communicate by default with the external (industrial) world only through Modbus over TCP. Is your LOGO controller able to communicate this way?

As per RS485, I am pretty sure you won't be able to communicate with Cerbo, maybe only if you use a separate USB to RS485 converter and then write a separate driver for that. The RS485 communication you'll find on VE.Bus ports is a proprietary one.

Alex

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Thank you for the information. Yes I believe TCP is the best way to communicate. Siemens LOGO controller can do that.

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mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi Alex,

I’m not sure why you’d say the Cerbo is a closed/proprietary system and not easy to integrate in an industrial environment?

All parameters are available on Modbus-TCP, running and used on many systems out there. And its the most easy to use protocol for integration into industrial environments, often using PLCs and SCADA systems.

For the IoT space we have MQTT, giving access to the complete internal databus. And available locally as well as remotely.

Then there is Node-RED, which (a) allows making custom automatisation, including adding a self-definable user interface if needed, on a GX. And (b) allows to implement further integration and protocols.

And for those wanting to go further, but now I’m well beyond integrating into an industrial environment, I know, the GX can be “rooted”, as you know, and then almost everything is possible. We have public available documentation on the data available on the internal databus (dbus). And lots of the code is open source.

The only thing we indeed don’t have is a Modbus server on RS485; but its not necessary for Logos, since it supports Ethernet.

For anyone looking to learn more:

  1. Read our whitepaper on datacommunication. Though I see that it needs updating (mention Cerbo and newer GX devices as well as MQTT and Node-RED).
  2. Modbus-TCP manual
  3. MQTT detailed documentation
  4. Venus OS large manual (includes Node-RED)

Have a good weekend!

Matthijs

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Alex Pescaru avatar image Alex Pescaru commented ·

Hi Matthijs @mvader (Victron Energy)

I stand corrected !

So you do talk and share ideas, despite some will say.... :-))) Just kidding, no offense I hope.

Indeed, you are offering a lot of things. Still, only the variables that you want to be offered.

If one wants to add to Modbus registers some other variables is not that easy...

For example, I wanted to get for the MultiRS, the ESS BatteryLife actual/current SOC limit...

It's not available as a dbus path for the MultiRS.

Instead, you can read the com.victronenergy.settings /Settings/CGwacs/BatteryLife/MinimumSocLimit and /Settings/CGwacs/BatteryLife/SocLimit, but those don't reflect the real life value.

For example, in this moment, my values inside MultiRS are both 30% and the above keys, read by ModbusTCP are reporting 10%. Also not changing if I change the limit for example with VictronConnect app.

I had to guess which Victron register is the actual SOC for MultiRS, despite of repeated asking on community here, and read it through CAN bus in order to make my automations.

Anyway, thanks for your response.

Alex

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