54
S
ect
io
n
4
Ta
g M
e
mor
y
M
a
p
Heat-resistive RFID System
User's Manual
Section 4
Reading from/Writing to Tags
Tag Memory Check Function
The DATA CHECK command (MD) performs a memory check. A CRC (Cyclic Redundancy Check)
code calculation, write, 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 75 is returned, and if they do not
coincide, end code 76 is returned as a
warning.
Command
Number of check block bytes in hexadecimal
(03
H
, 04
H
, ..., FE
H
, FF
H
, 00
H
)
* 00
H
: 256 bytes
Processing designation
(C: Comparison, K: Calculation)
Read/Write Head channel (always 1)
Check block start address
(0000
H
to 03E5
H
)
M
D
1
*
CR
× ×
C/K
@
× ×
FCS
× ×
× ×
Response
M
D
0
0
End code
00: Normal end (calculation processing only)
@
× ×
*
CR
FCS
75: Data normal (comparison processing only)
76: Data error warning (comparison processing only)
Area start
address
Address
CRC (rightmost)
CRC (leftmost)
0000
H
0001
H
→
Number of check
block bytes
Check code
calculation area
(Number of check
block bytes
−
2)
Check code area
(2 bytes)
