534
APPENDICES APPENDIX
Appendix 5 Operation Image and Data Structure of Predefined Protocol
Check code
■Processing procedure
C24 processes check code according to the following procedure.
1. Calculates value according to the selection of "Processing method".
2. When "Complement calculation" is 'One's complement' or 'Two's complement', performs a 2-word-wise complement
operation on the value calculated in the above 1.
3. When "Code type" is 'ASCII decimal', extracts the lowest one word from the value calculated in the above 2, and
performs the hexadecimal to decimal conversion.
■Calculation procedure for horizontal parity
The following show procedures for calculating horizontal parities using the following sample data.
For the packet shown above
HEX
C24
HEX
(Data flow) (Code type) (Processing method)
(Data length)
(Calculating range)
(Complement calculation)
Forward direction (upper byte → lower byte)
Reverse direction (lower byte → upper byte)
BIN → ASCII
conversion of
length value
Calculated
length value
Swapping
send data
Byte swap (by word)
*Only when the data
length specification is
4 bytes
ASCII
hexadecimal
ASCII decimal
Data transmission
(Data flow) (Code type) (Processing method)
(Data length)
(Calculating range)
(Complement calculation)
Calculated
check code
Forward direction (upper byte → lower byte)
Reverse direction (lower byte → upper byte)
Checking
ASCII → BIN
conversion of
length value
Swapping
receive data
Received
check code
Byte swap (by word)
*Only when the data
length
specification is 4
bytes
ASCII
hexadecimal
ASCII decimal
Data reception
STX “J” “7” “1” “C” “2” “4” ETX“R”
Horizontal
parity
Calculating range
“R”
0101 1011
XOR
0000 0011 0101 1000ETX (03
H
)
(52
H
)
“J” (4A
H
)
“7” (37
H
)
“1” (31
H
)
“C” (43
H
)
“2” (32
H
)
“4” (34
H
)
0101 0010
XOR
0100 1010 0001 1000
XOR
0011 0111 0010 1111
XOR
0011 0001 0001 1110
XOR
0100 0011 0101 1101
XOR
0011 0010 0110 1111
XOR
0011 0100
=
=
=
=
=
=
=
(Binary)
Horizontal parity = 58
(Hexadecimal)
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