3-6
Section
Memory Check Function
28
If the LOCK command is executed with the lock bits all set to 0, the command will
read the lock information that has been set for the ID Tag. A command code has
been added for the lock function.
The following table shows the configuration of the byte containing the lock infor-
mation. Bits 2 through 7 are the lock bits for pages 1 through 6. Bits 0 and 1 are
always 0.
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Page 6
Page 5
Page 4
Page 3
Page 2
Page 1
Set to 0.
Set to 0.
Once a page has been locked, it cannot be released.
3-5
Write Protect Function
The write protect function can be used to write-protect individual pages and pre-
vent the accidental loss of fixed information such as a pallet number or product
information.
The write-protect information can be set in the tag to write-protected individual
pages independently, so any region or combination of pages can be protected. A
protection error will occur if the WRITE command is executed on a write-pro-
tected page.
There is one write-protect bit is assigned to each page, for a total of 30 bits. Set
the corresponding bit to 1 to write-protect a particular page. Set the correspond-
ing bit to 0 to clear the write-protection on a particular page. The following dia-
gram shows the configuration of the protection information (4 bytes or 32 bits)
used in the WRITE PROTECT command. Refer to 5-6-11 WRITE PROTECT
(WP) for more details.
Protection information
Page 30
b7
Page 29
b6
Page 24
b1
Page 23
b0
Page 22
b7
Page 21
b6
Page 16
b1
Page 15
b0
Page 14
b7
Page 13
b6
Page 8
b1
Page 7
b0
Page 6
b7
Page 5
b6
Page 2
b3
Page 1
b2
b1
b0
Always 0
Always 0
3-6
Memory Check Function
A check code is attached to data in the tag to indicate when an error has oc-
curred in the data due to an EEPROM overwrite or unknown cause. The formula
used to calculate the CRC code is: X
16
+ X
12
+ X
5
CHECK (MC) and 5-6-9 MEMORY CALCULATE (MK) for more details.
The memory check is performed using the MEMORY CALCULATE command
(MK) that writes the check code and the MEMORY CHECK command (MC) that
verifies the check code.
The check block is specified by the first address and the number of bytes (n) indi-
cated in the command. The first part of the check block (n–2 bytes) is the calcula-
Lock Information
Precaution
Configuration of the
Check Block Area
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