Modbus in Node-red

Hi all

I am a complete beginner when it comes to modbus, This project is part of solar power installation, I am trying to retrieve the data logged on a morningstar sunsaver mppt controller through modbus.
my set up so far is a Raspberry pi with a gpio serial port connecting to the morningstar meter bus then to the morningstar sunsaver MPPT,
I have node-red installed and runnng but i am having trouble configuring node-red to read the MPPT.

am i trying the impossible for a beginner? thoughts and suggestions are welcome

Wat is topology of the network that Modbus TCP & Modbus RTU that is configured rasperry dont support Modbus TCP as per OEM instructions ...

We need to know the architecture of the system ..which protocol is used ...RS485....Or other support...

Node red installed ok but you need to give right instructions to be able to read registers values at least....

See this video it can help ..same configuration but this is for VFD DRIVE...

Any time!

Hi an thank you for your suggestions. I am busy with work at the moment so will look at the links later. but for now this is what i have.

An RS 232 serial port connected via the gpio 14 and 15 with 3v supply to a morningstar meter bus which then connects to the sunsaver mppt RJ11 socket .

this is the meterbus

this is the modbus protocol for the MPPT, its RTU .

I have activated UART and disabled console on the raspi. but confused as to how to set the baud rate.

I will get time tomorrow to check those links you gave, thank you
Thank you for the links very interesting.

So now im trying to relate this to my project,

In node-red do I need to create a Modbus server or is that just for TCP, ( the mppt is RTU) or can i just use the read or getter nodes, I dont understand which would be suited to my system.

secondly when i come to complete the Properties fields in the Modbus-server-node the fields for coils, holdings, inputs and discretes are in what looks like a decimal format. How does that translate from the PDU or Logical address that i have from the Modbus protocol for the MPPT.

Thank you for the feddback

You have to use the Rapserry pi as Modbus TCP /RTU gateway....

A skecth /draft /drawing of yor installation would be welcome for better support..