Modbus support

[hiperiondev]

Excellent project!
Since it could have interesting industrial uses, it would be important to add Modbus access.

[pcting]

I think something like using this modbus lib might be a good start (https://github.com/emelianov/modbus-esp8266)

for my use case, i have a solaredge inverter with a meter installed. the meter is connected to the inverter through rs485 and the meter has CT clamps reading my mains amps. the meter supports the sunspec open standard. iotawatt can implement this specification and therefore replace the solaredge meter.

in my deployment, the solaredge inverter has an ip and through this ip, i can query for the modbus tcp endpoint. i use this endpoint for home assistant integration through the ha-sunspec plugin.

[pcting]

another use case:

this one is an rs485 use case. i have a soyo grid-tie inverter i've been playing around with and it has an a meter that also communicates through rs485 to provide consumption limiting. there's this project here that simulates the meter (https://github.com/syssi/esphome-soyosource-gtn-virtual-meter).

[pcting]

stepping back from all this, it's probably easier just to build a separate modbus device that polls iotawatt for metrics. but building in modbus support natively would be really nice