modbus communication


Steve Myres, PE

The two implementations of the Modbus protocol are Modbus RTU and Modbus ASCII. In Modbus ASCII, the data are transmitted in text form, i.e., an integer value of 45 is sent as the string "45" (or rather, as the binary for the ASCII characters "4" and "5"), whereas in Modbus RTU, 45 is represented directly in binary (0010 1101).

Filipe Campos

There is another important diference. In RTU the security is made by CRC calculation and in ASCCI is made by LRC calculus.

Filipe Campos