RFID Communications

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.

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

 

 

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.

Command from Host

MSB

LSB

Remarks

AAH

95H

Perform Command 95

 

 

 

00H

00H

Tag Family 00/Reserved

 

 

 

00H

01H

Start Address

 

 

 

00H

04H

Read Length

 

 

 

07H

D0H

2-second Timeout

 

 

 

00H

ABH

SN byte 0

 

 

 

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

 

 

 

Response from Controller

MSB

LSB

Remarks

AAH

95H

Command Echo

 

 

 

00H

30H

Data byte 1

 

 

 

00H

31H

Data byte 2

 

 

 

00H

32H

Data byte 3

 

 

 

00H

33H

Data byte 4

 

 

 

FFH

FFH

Message Terminator

 

 

 

85

LRP2000 Passive Reader/Writer

Page 90
Image 90
Escort LRP2000 manual ABxS Command 95H SN Read, Abh, F3H