4-4
Section
FCS Calculation
56
4-4
FCS Calculation
FCS (Frame Check Sequence) can be attached to output data to
improve communications. (For normal communications only).
FCS is the result of taking the XOR for each byte between header
and footer (8 bits) and converting to 2-character ASCII codes.
Each time data is received, the host link calculates the FCS and
checks it against the FCS attached to sending data so that send-
ing data can be checked for errors. Refer to
Appendix B FCS
Check Program Examples (BASIC).
→
(e.g.) Reading data:ABCDEFG
The sending data is as shown below.
Header
Footer
Reading data
FCS
Calculation
ASCII
code
A
41
0100
0001
XOR
B
42
0100
0010
XOR
C
43
0100
0011
XOR
D
44
0100
0100
XOR
XOR
E
45
0100
0101
XOR
F
46
0100
0110
XOR
G
47
0100
0111
Result
0100
0000
Converted into hexadecimal
and used as ASCII codes.
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