Automation Direct DURApulse GS4 User Manual page 322

Chapter 5: Serial Communications
Chk (
CheCk sum
ASCII Mode:
LRC (Longitudinal Redundancy Check) is calculated by summing up module 256, the values of the
bytes from ADR1 to last data character, then calculating the hexadecimal representation of the
2's-complement negation of the sum.
For example, reading 1 word from address 0401h of the AC drive with address 01h.
RTU Mode:
Page 5–16
)
Command Message
STX ':'
'0'
ADR 1
ADR 0
'1'
'0'
CMD 1
CMD 0
'3'
'0'
'4'
Starting data
address
'0'
'1'
'0'
Number of data
'0'
(Count by word)
'0'
'1'
'F'
LRC CHK 1
LRC CHK 0
'6'
CR
END 1
END 0
LF
Response Message
ADR
CMD
Starting data address
Number of data (Count by word)
CRC CHK Low
CRC CHK High
DuRA
pulse
01h+03h+04h+01h+00h+01h=0Ah;
the 2's complement negation of 0Ah is F6h�
01h
03h
21h
02h
00h
02h
6Fh
F7h
GS4 AC Drive User Manual – 1st Ed, Rev A - 10/20/2017