Omron V530-R160E User Manual page 230

SECTION 8
Communication with the Host
 FCS Calculation
FCS is the result of taking the XOR for each byte between the header and footer (8 bits) and con-
verting to 2-character ASC ll code.
The FCS (Frame Check Sequence) can be attached to output data to improve communications.
Each time data is received, the host link calculates the FCS and checks it against the FCS
attached to the sent data so that the sent data can be checked for errors.
For details on an FCS check program, see SECTION 10 Appendix FCS Check Program Exam-
ple (BASIC).
Refer to page 278 (SEC.10).
An FCS can only be appended if the communications mode is Normal.
Example: Reading data: ABCDEFG
• Reading data
Header
• Calculation
Reading data
A
B
C
D
E
F
G
V530-R160
228
Operation Manual
Refer to page 206.
The details of the reading data and calculation method are as follows.
A B C D
Reading data
ASCII code
On conversion
to ASCII code:
E F G 4 0
FCS
41
On conversion
42
to hexadecimal
notation:
43
44
45
46
47
FCS data: 4
Footer
Hexadecimal
notation
0100 0001
XOR
0100 0010
XOR
0100 0011
XOR
0100 0100
XOR
0100 0101
XOR
0100 0110
XOR
0100 0111
On obtaining the exclusive
logical sum:
0100 0000
On conversion
to ASCII code:
0