Delta ASDA-B2-F Series User Manual page 191

Communications
RTU Mode:
Slave Address
8
The start and the end of the communication in RTU (Remote Terminal Unit) mode are silent
intervals. The communication address, function code, data content and error checking CRC
(Cyclical Redundancy Check), etc. are between the start and the end.
Example 1: function code 03H, accessing multiple words:
The master issues command to the 1
data address 0200H. In response message from the slave, the content of start data address
0200H is 00B1H, and the content of the 2
in one single access is 10. The calculation of LRC and CRC will be described in the following
section.
ASCII Mode:
Command Message (Master):
Slave Address
Function
Start Data Address
Data Number
(in word)
LRC Check
End 1
End 0
8-6
Start A silent interval of more than 10 ms
Communication address: 1 byte
Function Function code: 1 byte
Data (n-1)
....... Data content: n word = n x 2 byte (n<=10)
Data (0)
CRC Error checking: 1 byte
End 1 A silent interval of more than 10 ms
Start ':'
'0'
'1'
'0'
'3'
'0'
'2'
'0'
'0'
'0'
'0'
'0'
'2'
'F'
'8'
(0DH)(CR)
(0AH)(LF)
st
slave and reads continuous 2 words starting from the start
nd
data address is 1F40H. The maximum allowable data
Response Message (Slave):
Start
Slave Address
Function
Data Number
(in byte)
Content of Start Data
Address 0200H
Content of Second Data
Address 0201H
LRC Check
End 1
End 0
ASDA-B2-F
':'
'0'
'1'
'0'
'3'
'0'
'4'
'0'
'0'
'B'
'1'
'1'
'F'
'4'
'0'
'E'
'8'
(0DH)(CR)
(0AH)(LF)
September, 2015