Chapter 8  MODBUS Communications| ASDA-A&A+ Series 
8-12     Revision April 2009 
RTU Mode:  
Command message:  Response message:  
ADR 01H  ADR 01H 
CMD 03H  CMD 03H 
02H (Upper bytes)   
Starting data 
address 
00H (Lower bytes)   
Number of data 
(Count by byte) 
04H 
00H 
 
00H (Upper bytes) 
Number of data 
(Count by word) 
02H 
 
Contents of starting 
data address 
0200H 
B1H (Lower bytes) 
CRC Check Low  C5H (Lower bytes) 
 
1FH (Upper bytes) 
CRC Check High  B3H (Upper bytes) 
 
Contents of second 
data address 
0201H 
40H (Lower bytes) 
  CRC Check Low  A3H (Lower bytes) 
 
 
CRC Check High  D4H (Upper bytes) 
Command code: 06H, write 1 word  
For example, writing 100 (0064H) to starting data address 0200H of ASDA-A and ASDA-A+ series with 
address 01H. 
ASCII Mode:  
Command message:  Response message:  
STX ‘:’  STX ‘:’ 
‘0’   ‘0’ 
ADR 
‘1’  
ADR 
‘1’ 
‘0’   ‘0’ 
CMD 
‘6’  
CMD 
‘6’ 
‘0’   ‘0’ 
‘2’   ‘2' 
‘0’   ‘0’ 
Starting data 
address 
‘0’  
Starting data 
address 
‘0’ 
‘0’   ‘0’ 
‘0’   ‘0’ 
‘6’   ‘6’ 
Content of data 
‘4’  
Content of data 
‘4’ 
‘9’   ‘9’ 
LRC Check 
‘3’  
LRC Check 
‘3’ 
End 1  (0DH)(CR)    End 1  (0DH)(CR) 
End 0  (0AH)(LF)    End 0  (0AH)(LF) 
 
 
 
 
Call 1(800)985-6929 for Sales
Call 1(800)985-6929 for Sales