Omron V600 User Manual page 110

Section 4
Functions
Memory Check Function in Data Carrier
A memory check can be made using the DATA CHECK command (MDC/K). A CRC (Cyclic
Redundancy Check) code calculation, overwrite, and comparison are made, using the check block
units specified by the user. The CRC code is calculated from the generated polynomial expression x
+ x 12 + x 5 + 1.
The calculation area is the portion of the check
block specified by the start address and the
number of bytes excluding the last two bytes.
The last two bytes are the check code area.
When check
(transaction code: K), the CRC of the
calculation area data is calculated and written
to the check code area. When data comparison
is specified (transaction code: C), the CRC of
the calculation area data is calculated and a
comparison made with the check code area
data. If they coincide, end code 00 is returned,
indicating normal transmission, and if they do
not coincide, end code 76 is returned as a
warning.
For details on the command format, refer to DATA CHECK (MDC/K).
Example Using the Data Carrier's DATA CHECK Command
In the following example, the data in address 0010H to 0012H is checked.
1. In this example, the following data already exists in
the memory.
RFID System
108
User's Manual
code write is
p.86
12
0010
H
34
0011
H
56
0012
H
0013
0014
Address
0000
0001
Area start
specified
address
Number of check
block bytes
2. Execute MDK1001005 (calculation transaction).
The CRC code 5CD6 calculated from the data
123456 is written to addresses 0013H and
0014H.
Check code calculation area
(Number of check
block bytes - 2)
CRC (upper digit)
Check code area (2 bytes)
CRC (lower digit)
12
0010
H
34
0011
H
56
0012
H
0013 5C
H
0014 D6
H
16