User Guide

Table Of Contents
Allegro/Title-21 Tag Commands
63
Write Request (24h; A003h)
The Write Request command writes data to the specified area of the specified tag. A non-
acknowledge (NACK) error response shall be returned if an invalid password was
included in the request. This command contains the following request fields:
Write Request Fields
Examples
An example command requesting ? be written to tag ? with a User Password = 0x? is:
Field Value Description
TM OpCode 0x24 TM OpCode for tag modification operations
Timeout [2 bytes] Indicates how long the command should spend
attempting the operation, in milliseconds.
TM Options 0x00 Reserved for Future Use.
Transaction Type Code 0xA003 Allegro/Title-21 code indicating operation to per-
form.
Options [1 byte] Command specific options
Page Number [2 bytes] Indicates which page of the tag is to be written to.
Tag ID [4 bytes] Optional, based on value of Options parameter.
Indicates the ID of the tag to operate on.
User Password/
Global Password
[4/8 bytes] Optional, based on the value of the Options param-
eter. The password to operation on the tag, if
required.
Page Data Byte Count [1 byte] Indicates the number of data bytes to follow.
Page Data Bytes [N bytes] Data to write to the tag.
FF 0E + N 24 ?? ?? 00 A0 03 ?? ?? ??
SOH Length TM
OpCode
Timeout
(ms)
TM
Option
Transaction
Type Code
Option Page
Number
?? ?? ?? ?? ?? ?? ?? ?? ?? NN NN ?? ??
Tag ID User/Global
Password
Page
Data
Count
Page Data CRC