This evidence although simulate other tests carried out in previous Post implemented Arduino and protocol Modbus RTU serial master mode, is the first step for connecting arduino an environment Scada Industrial we will see more before implementing Modbus TCP IP, if you want to see continue in PDAControl final application.
Other Implementations Arduino and Modbus RTU:
Modbus RTU Master Library tests with Arduino
Modbus RTU Master tests with Arduino via RS232 and screen Panasonic GT01
Modbus RTU Master tests with Arduino via RS232 and PLC Panasonic FPX C14R
Explanation of Application
In this test we will read a potentiometer 100k connected to the input analog 0, the value of ADC0 0-1023 be transmitted via Modbus RTU Simulator Master Modbus in Holding Register  and this transmitted value is displayed on the display oled Connected to the Arduino via I2C.