Energymeter Simulation with Modbus/ Slave

Hi all,
I've got an Solis PV Inverter which is normaly connected by Modbus to an Acrel Acr10r Energymeter. I can't use the Acrel Meter for some reason. I've got a Finder Energymeter installed. The Finder Energymeter can measure the equivalent values, but they are stored in different registers and different formats.

I can readout all necessary values of the FinderMeter by Modbus in Node-Red. That's ok. But I'm stucking now how I can supply the new values to the inverter. I know what the Inverter is asking for (register+data). But I can't see how to build it in node-red.

Normaly the Solis Inverter asks ID=1 for a bunch of registers, but how to serve them in Node-Red I could not find a kind of "Slave" Node. I'm working with the "node-red-contrib-modbus" Nodes

My readout of the FinderMeter is this:

Thank you very much in advanced for your help!

Hi Chris,

I'm currently facing the same issue. Essentially, I'm looking to configure an energy meter of one type to function as a Modbus RTU slave for another device. Unfortunately, I'm unsure of how to set it up as a slave.

Fortunately, there are plenty of knowledgeable individuals on the forum who have likely tackled this problem numerous times.

The contrib-modbus package includes a modbus-server node which, according to the documentation, looks as if it should do what you want. I have not used it myself though.

thank you, I think I got the principal of the slave function:

You need to place a Modbus-Server-Node. It looks like it just should be here and be configured for IP Adress and so on (not much input/ output).

Then you need to write the values into the registers of the Modbus-Sverver-Node with the FlexWriter Node. But they are not connected with wires like I would have sugested, Its like writing to any other Modbus item.

Now the Modbus-Server-Node is replying the bevore seted values if asked for with FlexGetter for example.

I will try to build this up and give an other reply.


As described in the help text, you can also feed in values by injecting messages directly into the node.

The modbus-server-node is only for Modbus TCP, correct? Or is there a way to act as a Motbus RTU slave?

Apparently so. I don't know of a serial server.