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SECTION 5
RF Ta
g Memory
Che
c
k
RFID System
User's Manual
SECTION 5
ID Sensor Unit Functions
RF Tag Memory Check
The Memory Check command performs an RF Tag 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.
A memory check is performed by using the Data Check command
with a Calculation processing specification to write the check code
and a Verification processing specification to verify the check code.
The start address and the number of bytes determine the specified
check block. All but the last 2 bytes are the area to calculate and the
last 2 bytes are the check code area.
When the Data Check command is executed to write the check code,
the CRC code is calculated for the area to calculate and written in the
check code area.
When the Data Check command is executed to verify the check code, the CRC code is calculated for the area
to calculate and compared with the data in the check code area. If the calculated code is the same as the data
in the check code area, the Normal End Flag (CIO n+7, bit 01) in Unit Status will turn ON. If they are not the
same, the Error End Flag (CIO n+7, bit 02) in Unit Status will turn ON, and the Status Flag (CIO n+8, bit 04) in
the Results Information will turn ON as a warning.
• Application Method
After writing the data, the Data Check command is executed with a Calculation processing specification to
calculate and write the check code. Before reading the data, the Data Check command is executed with a
Verification processing specification to verify the check code. This enables detecting internal data corruption
that might occur in the RF Tag when the data is not being accessed.
Area start
address
CRC (upper digit)
CRC (lower digit)
Address (hex)
Check code
area (2 bytes)
Area for check
code calculation
(number of check block
bytes minus 2)
Number of
check block
bytes
00
01
Data written
Check code calculated
Check code verified
Data read
Write stage
Read stage
Summary of Contents for CJ1W-V680C11
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