User's Manual

MP9310 User’s Guide
30
Overview of the Tag Writing Commands
Tag writing with SAMSys readers is performed using the Write Any (Wa)
command and the Write Tag (Wt) command. Wa must be used when writing to
blank tags. Wt is used when the tag already has a tag ID.
Typically, Wa is used whenever the write operation affects the tag ID. Wa can also
be used for write operations to any data on a tag. This command is executed with
a single tag in the RF field.
Wtcan only be used for write operations to a specific tag where the tag ID has
already been assigned. This command can be used for write operations to any data
on the tag, except the tag ID itself.
Both Wa and Wt have several different command parameters that can occur in any
order in the command string. In some cases, the parameters are optional. The
parameters include the following:
• a: address block (in hex)
• l: length
• b: write data
• f: control flags
Where:
a: address block refers to the particular piece of writeable memory in the tag. The
concept of a block size can vary from one tag type to another. The address block
may be optional if the specific tag type only contains a single piece of writeable
memory. This value is in hexadecimal.
l: length refers to the length of the data to be written. For some tags this length is
in bytes and for others this is in blocks.
b: write data is the data to write to the tag.
f: control flags dictate certain optional protocol specific behavior with the write
operation.
Some tags support the ability to have a portion or all of their internal memory
locked against further modification. Write operations to locked memory will not
be successful. The locked status of a piece of memory can be queried via the Yl
command. The Yl response is
f:0 for unlocked or f:1 for locked.
Details of the syntax for any command found in this document can be obtained in
the CHUMP Reference Guide.