8-16
RTU Mode
Command message PC
Servo
Response message Servo
PC (OK)
Servo
PC (ERROR)
ADR
01H
ADR
01H
ADR
01H
CMD 10H
CMD
10H
CMD
90H
Starting
Data
Address
(MSB) 01H
Starting
Data
Address
(MSB) 01H
Error Code 02H
(LSB) 00H
(LSB) 00H
CRC LSB
CDH
Data Length
(Calculated by word)
00H
Data Length
(Calculated by word)
00H
CRC MSB
C1H
02H
02H
Data
(Number of Bits)
04H
CRC LSB
40H
Write Data
to 0100H
(MSB) 00H
CRC MSB 34H
(LSB) 64H
Write Data
to 0101H
(MSB) 01H
(LSB) 2CH
CRC LSB
BFH
CRC MSB
ADH
LRC (ASCII Mode) and CRC (RTU Mode) Check Digit
LRC Check Digit:
ASCII Mode uses LRC (Longitudinal Redundancy Check) Check Digit.
The LRC Check is to calculate the sum of ADR, CMD, starting data address, and data contents, after the
sum is divided with the unit in 256 (100H) and take the remainder (if the total sum is 19DH, then take
9DH), and the remainder is calculated in 2's complement, the final result calculated is the LRC Check Digit.
For example: Use Diagnostic Function on the Driver with ID 01H.
STX ‘ : ’
Data Content
(word Format)
‘ A ’
ADR
‘ 0 ’ ‘ 5 ’
‘ 1 ’ ‘ 3 ’
CMD
‘ 0 ’ ‘ 7 ’
‘ 8 ’
LRC
‘ 1 ’
Sub-
function
Code
(MSB)
‘ 0 ’ ‘ B ’
‘ 0 ’ END1 (CR) (0DH)
(LSB)
‘ 0 ’
END0 (LF) (0AH)
‘ 0 ’
01H+08H+00H+00H+A5H+37H = E5H
Take E5H 2's complement is 1BH, so the LRC is '1', 'B'
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