RFID Communications
LRP2000 Passive Reader/Writer 82
6.4.20 ABxS Command 91H: Memory Lock All
DESCRIPTION
Command 91H locks contiguous blocks of read-write memory. Once bytes are locked, they cannot be
written to, nor can they be unlocked.
DISCUSSION
The memory can be locked only in contiguous blocks. The command passes one parameter for the first
block and another parameter for the number of blocks to be locked. This is one of only two ABx commands
that address the memory of the tag using these parameters. The block structure of the tags is governed by
the ISO-15693 specification. Attempting to write to locked bytes returns a Write Security Error.
The command is formatted as shown below.
Example
This example locks blocks 0-7 on all tags in range with the Family ID of 02H. Two tags are found and
locked.
Field Remarks
Command Command number in hex preceded by AAH
Family Code Tag Family ID - 00H = all tags
Reserved 00H
Timeout Timeout value given in 1 ms units (001EH - FFFEH)
First Block First block of memory to lock
Number of Blocks Number of contiguous blocks of memor y to lock
Message Terminator FFFFH
Command from Host Response from Controller
MSB LSB Remarks MSB LSB Remarks
AAH 91H Perform Command 91 AAH 91H Command Echo
02H 00H Family ID/Reserved 02H 08H Ntag/Status
07H D0H 2-second Timeout FFH FFH Message Terminator
00H 08H Lock Configuration
FFH FFH Message Terminator