There are two ways of programming this piece of hardware: Program both the AVR chip on the Arduino board and the ESP8266 chip on the ESP-12E/F board. Program only the AVR chip on the Arduino board.

The schematics are available in eagle files in the "pcb" folder and printable pdf files fot pcb etching. Figure 1 - Interface provided by the esp8266 webserver. Figure 2 - Assembled board. 4.5 to 9V ...

It is built around an Espressif NodeMCU board fitted with an ESP8266. The Modbus protocol is widely used ... to the 24 V level compatible with the industrial environment. The schematic diagram in ...