Delta Electronics ASDA-B Series manual LRC Ascii Mode

Chapter 8 MODBUS CommunicationsASDA-B Series

RTU Mode: Command message:

Response message:

ADR	01H
CMD	06H
Starting data	02H (Upper bytes)
address	00H (Lower bytes)
Content of data	00H (Upper bytes)
	64H (Lower bytes)
CRC Check Low	89H (Lower bytes)
CRC Check High	99H (Upper bytes)

LRC (ASCII Mode):

ADR

CMD

Starting data

address

Content of data

CRC Check Low

CRC Check High

01H

06H

02H (Upper bytes)

00H (Lower bytes)

00H (Upper bytes)

64H (Lower bytes)

89H (Lower bytes)

99H (Upper bytes)

LRC (Longitudinal Redundancy Check) is calculated by summing up, module 256, the values of the bytes from ADR 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 0201H of the ASDA-B series AC servo drive with address 01H.

STX	‘:’
ADR	‘0’
	‘1’
CMD	‘0’
	‘3’
	‘0’
Starting data address	‘2’
	‘0’
	‘1’
	‘0’
Number of data	‘0’
	‘0’
	‘1’
LRC Check	‘F’
	‘8’
End 1	(0DH)(CR)
End 0	(0AH)(LF)

01H+03H+02H+01H+00H+01H = 08H, the 2’s complement negation of 08H is F8H.

Hence, we can know that LRC CHK is ’F’,’8’.

8-12 Revision January 2009