Omron V680-CA1D User Manual page 56

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
Command
× ×
@
Processing designation
(C: Comparison, K: Calculation)
Read/Write Head channel (always 1)
Check block start address
(0000 to 03E5
H
Response
× ×
@
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.
Heat-resistive RFID System
54
User's Manual
× ×
M D C/K 1
)
H
*
M D 0 0
FCS
End code
00: Normal end (calculation processing only)
75: Data normal (comparison processing only)
76: Data error warning (comparison processing only)
× × × ×
*
FCS
Number of check block bytes in hexadecimal
(03 , 04
H
* 00 : 256 bytes
H
CR
Address
0000
H
0001
H
Area start
→
address
Number of check
block bytes
16 + x 12 + x 5 + 1.
CR
, ..., FE , FF , 00 )
H H H H
Check code
calculation area
(Number of check
block bytes − 2)
CRC (leftmost)
Check code area
(2 bytes)
CRC (rightmost)