ASCII vs RTU example:
Using the same example shown above to request registers 40108 to 40110 from slave address 17.
11 03 00 6B 00 03
The complete ASCII request is made by first adding the message delimiting characters. A colon is added to the start of the message, the LRC, carriage return and line feed are added to the end:
: 1 1 0 3 0 0 6 B 0 0 0 3 7 E CR LF
Each character is now treated as an ASCII character and replaced with it's hex value to give the final message.
3A 3131 3033 3030 3642 3030 3033 3745 0D 0A
This Modbus ASCII request size is 17 bytes (170 bits)
...............
The equivalent Modbus RTU message would be:
11 03 00 6B 00 03 76 87
This Modbus RTU request size is 8 bytes (80 bits)
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