I am working on a Modbus TCP connection to my Classic 150. I am using a Wemos D1 (ESP8266) and Arduino software. There is also a connection to my phone via Blynk.
I am currently reading the register 4115-4122. These are
4115 Average Battery Voltage (1 sec)
4116 Average PV terminal input Voltage (1 second average)
4117 Average Battery Current (1 sec)
4118 Average Energy to the Battery This is reset once per day
4119 Watts Average Power to the Battery
4120 Charge Stage
4121 Average PV terminal input Current. (1 second average)
4122 Last measured open-circuit Voltage at the PV terminal input.
Other Hreg value could be added if they would be useful.
My goal is to just monitor the Midnite Classic and turn on various loads once the battery is full or near full. I would like help coming up with a strategy of when to turn on a load and then a second or third load as needed. Only one of my loads could be used with PWM and it would normally be lower priority than the other load options.
Look in open source area of forums here.
Also Classic DIY has project to send out data on mqtt . From there you can use Node Red to control whatever you want.
https://github.com/ClassicDIY
Larry