Mitsubishi FX3U Series User Manual page 49

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FX
Series Programmable Controllers
3U
User's Manual - MODBUS Serial Communication Edition
The following is a calculation example in the case where function code 07H is sent to station No. 2.
CRC error check procedure
(Load the register whose 16 bits are all "1")
02
(Station No.)
H
Exclusive OR (XOR)
Shift 1
Generator polynomial
Exclusive OR (XOR)
Shift2
Generator polynomial
Exclusive OR (XOR)
Shift3
Shift4
Generator polynomial
Exclusive OR (XOR)
Shift5
Shift6
Generator polynomial
Exclusive OR (XOR)
Shift7
Shift8
Generator polynomial
Exclusive OR (XOR)
07
(Function)
H
Exclusive OR (XOR)
Shift 1
Generator polynomial
Exclusive OR (XOR)
Shift2
Generator polynomial
Exclusive OR (XOR)
Shift3
Generator polynomial
Exclusive OR (XOR)
Shift4
Shift5
Generator polynomial
Exclusive OR (XOR)
Shift6
Shift7
Shift8
CRC value
Address field
Function code
(02
)
(07
H
16-bit register (MSB)
1111
1111
1111
0000
1111
1111
1111
0111
1111
1111
1010
0000
0000
1101
1111
1111
0110
1111
1111
1010
0000
0000
1100
1111
1111
0110
0111
1111
0011
0011
1111
1010
0000
0000
1001
0011
1111
0100
1001
1111
0010
0100
1111
1010
0000
0000
1000
0100
1111
0100
0010
0111
0010
0001
0011
1010
0000
0000
1000
0001
0011
0000
1000
0001
0011
0100
0000
1001
1010
0000
0000
1110
0000
1001
0111
0000
0100
1010
0000
0000
1101
0000
0100
0110
1000
0010
1010
0000
0000
1100
1000
0010
0110
0100
0001
0011
0010
0000
1010
0000
0000
1001
0010
0000
0100
1001
0000
0010
0100
1000
0001
0010
0100
12
H
CRC (Error check)
)
(41
)
(12
H
H
7 MODBUS Standard Commands
7.2 Frame Specifications
Carry
Flag
1111
0010
1101
1110
1
0001
1111
1111
1
0001
1110
1111
0
1111
1
0001
1110
1111
0
1111
1
0001
1110
1111
0
1111
1
0001
1110
0111
1001
1100
1
0001
1101
1110
1
0001
1111
0111
1
0001
0110
0011
0
1001
1
0001
1000
0100
0
0010
0
0001
0
41
H
)
H
45
1
2
3
4
5
6
7
8
9
10

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