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Electromagnetic Inductive RFID System
User's Manual
SECTION 3
Functions
Memory Check Function
A check code can be added to the data in a Tag to detect errors from memory write life or unexpected causes.
The polynomial X 16 + X 12 + X 5 + 1 is used to generate a CRC code as the check code.
Use the Memory Check command (MD) to write and verify commands.
In the check block, which is specified using the start
address and the number of bytes, all but the last two bytes
are the calculation area. The last two bytes of the block are
the check code area.
When a Check Code Write command is sent, the CRC
code for the data in the calculation area is calculated and
written to the check code area. When a Data Verify
command is sent, the CRC code for the data in the
calculation area is calculated and compared to the data in
the check code area. When the data matches, “0” is
returned as the response status flag to indicate that the
data is normal. If the data does not match, “1” is returned
as a warning.
Calculate and write the check code using the Memory Check command (MD) after writing data and verify the
check code before reading data. This enables detecting in advance data corruption in Tags that can occur
while the Tags are not being accessed.
Refer to Memory Check (MD) when using the Memory Check function.
p.48
Check code calculation area
(check block bytes
−
2)
Area start address
Check code area (2 bytes)
Address
00
01
CRC (leftmost)
CRC (rightmost)
Data write
Check code calculation
Check code verification
Data read
Writing stage
Reading stage