Omron C200H-ASC11, Manual, Page: 166 / 301

7-6
Section Details of BASIC Commands
157
fcs
Syntax:
FCS
(<string expression>[, <fcs type>])
Description: Function. Calculates the frame checksum of a string expression.
The
FCS
is calculated by performing one of the following operations on all bytes in the string
expression.
The type of
FCS
calculation is selected by <fcs type>. This is an integer value in the range: [0…9].
The following calculations can be performed. The type of the return depends on whether a
BINARY
or
ASCII
calculation is requested.
BINARY
calculations return integers and
ASCII
calculations return character strings.
FCS code data <fcs type> Calculation method
Data type Number of
bytes
0 Binary 1
1
LRC
ASCII 2
2 Binary 2
3
CRC-CCITT
ASCII 4
4 Binary 1
5
SUM (1 byte)
ASCII 2
6 Binary 2
7
SUM (2 bytes)
ASCII 4
8 Binary 2
9
CRC-16
ASCII 4
Remarks:
Note: 1. The calculation logic for CRC-CCITT is XMODEM.
2. The calculation logic for CRC-16 is MODBUS. For example, character string data is
handled as follows:
Examples: > 10 B$ = “RD89”
> 20 PRINT FCS(B$, 1)
> RUN
17
See also:
“1 2 3 4” = 31 32 33 34
x
n
+ x
n-1
…x
1
= x
0