MP9311 User’s Guide
36
Programming the ISO18000-6B Tag
In ISO18000-6B, operations are controlled by a state machine within the tag. As a result,
the tag must be in the
Data Exchange
state for the write operation to succeed. To
guarantee the tag is in that state, the tag must be reset using the Tag Reset
Tr
command
followed by a Read Detect
Rd
command prior to performing the first write operation.
The ISO18000-6B protocol does not provide any feedback on a global write operation and
the reader always provides an Ack (
{A
) after the tag receives a
Wa
command. The only
way to verify success is to read the data back from the tag.
An ISO18000-6B tag write operation can fail if any byte within the addressed range is
locked or if the power setting is not correct. It is not uncommon for Philips and Rafsec
ISO18000-6B tags to have a portion of the first eight bytes locked. Confirm the status of
the specific type of tag in use.
The
Wa
,
Wt
and
Wv
commands can be used with the ISO18000-B tag. The
Wt
command
is used to modify data outside of the first 8 bytes in the tag and requires specification of
the tag ID using the
d:
parameter. The
Wv
command is discussed at the end of this section.
The format of the
Wa
command is as follows:
}Wa,a:<blk addr>,b:<blk data>[,l:<# blks>]!
where:
a:<blk addr>
. In ISO18000-6B, this parameter provides the address of the
writeable memory block. The block size is one byte.
l:<# blks>
. This parameter reflects the number of blocks being written (which is
equal to the number of bytes in this case).
b:<blk data>
. This parameter contains the actual data being written.
The following command example command writes
AABBCCDD
to user memory at address
0x20
on a tag with ID
EF04001122334455
:
}wt,d:EF04001122334455,a:20,b:AABBCCDD,l:4!
In addition to the
Wa
and
Wt
commands, SAMSys readers also support the following
ISO18000-6B operations:
•
Lb
Lock Block
•
Yl
Query Lock Status (returns
f:0
for unlocked or
f:1
for locked)
Each of these operations must specify a particular tag ID with the
d:
parameter and block
address with the
a:
parameter.
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