Delta ASDA-B3 Series, User Manual

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MODBUS Communication ASDA-B3
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9
Example 1: function code 03H, read multiple words
When the master issues a read command to the first slave:
The slave reads two continuous words starting from the start data address 0200H. In the
response message from the slave, the content of the start data address 0200H is 00B1H and
the content of the second data address 0201H is 1F40H. The maximum allowable number of
data in one single access is 10.
ASCII mode:
Command Message (Master): Response Message (Slave):
Start ‘:’ Start ‘:’
Slave Address
‘0’
Slave Address
‘0’
‘1’ ‘1’
Function
‘0’
Function
‘0’
‘3’ ‘3’
Start Data Address
‘0’
Data Number
(in bytes)
‘0’
‘2’ ‘4'
‘0’
Content of Start Data
Address 0200H
‘0’
‘0’ ‘0’
Data Number
(in words)
‘0’ ‘B’
‘0’ ‘1’
‘0’
Content of the 2 nd Data
Address 0201H
‘1’
‘2’ ‘F’
LRC
‘F’ ‘4’
‘8’ ‘0’
End 1 (0DH) (CR)
LRC
‘E’
End 0 (0AH) (LF) ‘8’
End 1 (0DH) (CR)
End 0 (0AH) (LF)
RTU mode:
Command Message (Master): Response Message (Slave):
Slave Address 01H Slave Address 01H
Function 03H Function 03H
Start Data Address
02H (High)
Data Number
(in bytes)
04H
00H (Low)
Data Number
(in words)
00H
Content of Start Data
Address 0200H
00H (High)
02H B1H (Low)
CRC (Check Low) C5H (Low)
Content of the 2
nd
Data
Address 0201H
1FH (High)
CRC (Check High) B3H (High) 40H (Low)
CRC (Check Low) A3H (Low)
CRC (Check High) D4H (High)
Note: a silent interval of 10 ms is required before and after each transmission in RTU mode.