Mitsubishi Electric MELSEC iQ-R Series Reference Manual page 11

• Data (2 bytes): Start coil number specification (0000H), Number of read points (0008H)
Error check procedure
1 Convert the ASCII codes within the error check range into the RTU format
(binary).
2 Add the figures. (Excluding carries during addition.)
3 Change the result to a 2's complement. (Reverse the bits and add 01H.)
4 Convert the result to an ASCII code.
Data is stored in ASCII code as follows:
Data Address field
category
Value 02H
Character 0 2
RTU (binary) 0000 0010
ASCII code 30H 32H
The slave, which received the request message, recalculates the check code in the request message and determines
whether the message is correct or not.
Error check procedure
1 Convert the ASCII codes within the error check range into the RTU format
(binary).
2 Add the LRC value. (Excluding carries during addition.)
Normally, the addition result is zero.
Function code Start coil number
specification
01H 0000H
0 1 0
0000 0001 0000
30H 31H 30H
LRC in request message transmission
Address field (02H)
Function code (01H)
Start coil number specification (H)
Start coil number specification (L)
Read points (H)
Read points (L)
Addition result
Reversed bit value
01H
LRC value
LRC value (ASCII code)
Read points
0008H
0 0 0 0 0
0000 0000 0000 0000 0000
30H 30H 30H 30H 30H
LRC check when receiving a request message
Address field (02H)
Function code (01H)
Start coil number specification (H)
Start coil number specification (L)
Read points (H)
Read points (L)
LRC value
Addition result
1 FRAME SPECIFICATIONS
1.1 MODBUS Protocol Frame Specifications
0000 0010
0000 0001
0000 0000
0000 0000
0000 0000
0000 1000
0000 1011
1111 0100
0000 0001
1111 0101
F 5
46H 35H
Error check
F5H
0 8 F 5
0000 1000 1111 0101
30H 38H 46H 35H
0000 0010
0000 0001
0000 0000
0000 0000
0000 0000
0000 1000
1111 0101
0000 0000
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