108
Section 4Data Carrier
RFID System
User's Manual
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
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
(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).
p.86
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.
2. Execute MDK1001005 (calculation transaction).
The CRC code 5CD6 calculated from the data
123456 is written to addresses 0013H and
0014H.
Area start
address
Number of check
block bytes
Check code area (2 bytes)
Address
0000
0001
CRC (upper digit)
CRC (lower digit)
(Number of check
block bytes - 2)
Check code calculation are
To Next Page
Loading...
