ModbusConfig library for ESP8266/ESP32/Arduino.
The library process a modbus configuration file in JSON format and execute operations described in the file.
Each device connected to Rx/Tx pin (RS485 interface board) can have several operations block with different polling interval specified in a configuration file. Any operation has several parameters: SlaveID, function, address, len and operation name to visually distinguish operations. When a device (slave) polling interval has reached, the libriary invoke the callback function to send telemetry data to a cloud server or poll a slave device.
JSON configuration file should be uploaded to SPIFFS file system on ESP8266/ESP32 boards using corresponding tool: http://esp8266.github.io/Arduino/versions/2.0.0/doc/filesystem.html.