Siemens ATC5300, Руководство пользователя

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General Information
1.13 CRC Calculation (CHECKSUM for RTU)
ATC5300
Modbus Communication Protocol, Edition 03/2011, A5E02469001-02
15
Example of CRC calculation:
Frame = 0207h
CRC initialization 1111 1111 1111 1111
Load the first byte 0000 0010
Execute xor with the first 1111 1111 1111 1101
Byte of the frame
Execute 1
st
right shift
0111 1111 1111 1110 1
Carry=1, load polynominal 1010 0000 0000 0001
Execute xor with the polynominal 1101 1111 1111 1111
Execute 2
nd
right shift
0110 1111 1111 1111 1
Carry=1, load polynominal 1010 0000 0000 0001
Execute xor with the polynominal 1100 1111 1111 1110
Execute 3
rd
right shift
0110 0111 1111 1111 0
Execute 4
th
right shift
0011 0011 1111 1111 1
Carry=1, load polynominal 1010 0000 0000 0001
Execute xor with the polynominal 1001 0011 1111 1110
Execute 5
th
right shift
0100 1001 1111 1111 0
Execute 6
th
right shift
0010 0100 1111 1111 1
Carry=1, load polynominal 1010 0000 0000 0001
Execute xor with the polynominal 1000 0100 1111 1110
Execute 7
th
right shift
0100 0010 0111 1111 0
Execute 8
th
right shift
0010 0001 0011 1111 1
Carry=1, load polynominal 1010 0000 0000 0001
Load the second byte of the frame 0000 0111
Execute xor with the polynominal 1000 0001 0011 1001
Second byte of the frame
Execute 1
st
right shift
0100 0000 1001 1100 1
Carry=1, load polynominal 1010 0000 0000 0001
Execute xor with the polynominal 1110 0000 1001 1101
Execute 2
nd
right shift
0111 0000 0100 1110 1
Carry=1, load polynominal 1010 0000 0000 0001
Execute xor with the polynominal 1101 0000 0100 1111
Execute 3
rd
right shift
0110 1000 0010 0111 1
Carry=1, load polynominal 1010 0000 0000 0001
Execute xor with the polynominal 1100 1000 0010 0110
Execute 4
th
right shift
0110 0100 0001 0011 0
Execute 5
th
right shift
0010 0100 0000 1001 1
Carry=1, load polynominal 1010 0000 0000 0001
Execute xor with the polynominal 1001 0010 0000 1000
Execute 6
th
right shift
0100 1001 0000 0100 0
Execute 7
th
right shift
0010 0100 1000 0010 0