93
RFID System
User’s Manual
SECTION 4
Tag Memory Check
SECTION 4
Functions
Tag Memory Check
The DATA CHECK command (MD C/K) performs a memory check. A CRC (Cyclic Redundancy Check) code
calculation, write, and comparison are made using the check block unit specified by the user.
The CRC code is calculated from the generated polynomial expression x
16
+ 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 code write is specified (process designation:
K), the CRC of the calculation area data is calculated and
written to the check code area. When data comparison is
specified (process designation: C), the CRC of the calcu-
lation area data is calculated and a comparison made
with the check code area data. If they coincide, an end
code of 00 will be returned for the V680 command (75
will be returned for the V600 command), and if they do
not coincide, an end code of 76 will be returned as a
warning.
For details on the command format, refer to DATA CHECK (MD
C/K).
p. 125
Example of Tag Memory Check
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.
2) Execute MDSTK1001005 (code calculation).
The CRC code 5CD6 calculated from the data
123456 is written to addresses 0013
H and 0014H.
3)Execute MDSTC1001005 (code verification).
The normal response MD0010 will be returned if the
data coincides.
If a data error occurs, MD7610 (a data error warning)
will be returned.
Area start
address
Number of check
block bytes
Check code area
(2 bytes)
Address
0000
0001
CRC (leftmost)
CRC (rightmost)
(Number of chec
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