Chapter 9 Communication
ASDA-A2R Series
9-8
Revision December, 2014
RTU mode:
Command message (Master):
Response message (Slave):
Slave Address
01H
Slave Address
01H
Function 03H
Function 03H
Starting data
address
02H (High word)
Number of data
(In Byte)
04H
00H (Low word)
Number of data
(In Word)
00H
The content of
starting address
0200H
00H (High word)
02H
B1H
(Low
word)
CRC Check Low
C5H (Low word)
The content of the
2
nd
data address
0201H
1FH (High word)
CRC Check High
B3H (High word)
40H (Low word)
CRC Check Low
A3H (Low word)
CRC Check High D4H (High word)
Note: Before and after the transmission in RTU mode, 10ms of silent interval is needed.
Example 2: function code 06H, write single word:
The Master issues command to the 1
st
Slave and writes data 0064H to address 0200H. The
Slave sends the response message to the Master after the writing is completed. The
calculation of LRC and CRC will be described in next chapter.
ASCII mode:
Command message from the Master:
Response message from the Slave:
Start ‘
:
’ Start ‘
:
’
Slave Address
‘0’
Slave Address
‘0’
‘1’
‘1’
Function
‘0’
Function
‘0’
‘6’
‘6’
Starting data
address
‘0’
Starting data
address
‘0’
‘2’
‘2'
‘0’
‘0’
‘0’
‘0’
Data content
‘0’
Data content
‘0’
‘0’
‘0’
‘6’
‘6’
‘4’
‘4’
LRC Check
‘9’
LRC Check
‘9’
‘3’
‘3’
End 1
(0DH)(CR)
End 1
(0DH)(CR)
End 0
(0AH)(LF)
End 0
(0AH)(LF)
