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RFID Communications
85 LRP2000 Passive Reader/Writer
6.4.22 ABxS Command 95H: SN Read
DESCRIPTION
Command 95H reads data from a specified RFID tag.
DISCUSSION
This command is used to read segments of data from contiguous areas of tag memory. It is capable of
handling up to 48 bytes of data transferred to the host with one command if there is no tag Family ID. The
timeout value is given in 1 ms increments and can have a value of 001EH to FFFEH (65,534 ms). When
the timeout is set to 0, the controller returns a syntax error. The SN Read consists of a start address,
length, and timeout value followed by a serial number. The eight-byte serial number of the target tag is
specified. If the read length exceeds the last tag address, the controller will return error message in the
status byte. It returns a response when done or when the timeout expires. The data read from the tag is
returned in the LSB of the register, and the MSB is always 00H. A special error packet (AAH FFH) is sent if
the timeout expires.
Example
Reads four bytes of data from the tag specified by serial number starting at address 0001H. A timeout of 2
seconds (07D0H = 2000 x 1 ms increments) is set for the completion of the SN Read. The Family ID byte
is set to zero.
Field Remarks
Command Command number in hex preceded by AAH
Tag Family Tag Family ID - 00H = all tags
Reserved 00H
Start Address Tag address where the read will start
Read Length Numbers of tag addresses to be read
Timeout Timeout value given in 1 ms units (001EH - FFFEH)
Tag Serial Number The 8-byte tag serial number
Message Terminator FFFFH
Command from Host Response from Controller
MSB LSB Remarks MSB LSB Remarks
AAH 95H Perform Command 95 AAH 95H Command Echo
00H 00H Tag Family 00/Reserved 00H 30H Data byte 1
00H 01H Start Address 00H 31H Data byte 2
00H 04H Read Length 00H 32H Data byte 3
07H D0H 2-second Timeout 00H 33H Data byte 4
00H ABH SN byte 0 FFH FFH Message Terminator
00H 02H SN byte 1
00H F3H SN byte 2
00H 05H SN byte 3
00H 00H SN byte 4
00H 01H SN byte 5
00H 04H SN byte 6
00H E0H SN byte 7
FFH FFH Message Terminator