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