RFID Communications

6.4.2 ABxS Command 05H: Read

DESCRIPTION

Read data from contiguous bytes of the RFID tag's read/write memory.

DISCUSSION

This command is used to read bytes from contiguous areas of tag memory. The minimum length of the data read from the tag is 1 byte. The maximum is the entire read/write address space of the tag. 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 Read command consists of a start address and length, followed by the message terminator, FFFFH, as shown below. If the read range exceeds the last tag address, the controller returns error message 21H, invalid format. The data read from the tag is returned in the least significant byte (LSB) of the word, and the most significant byte (MSB) is always 00H.

Field

Remarks

Command

Command number in hex preceded by AAH

 

 

Start Address

Tag address where the read starts

 

 

Read Length

Number of tag addresses to be read

 

 

Timeout

Timeout value given in 1 ms units (001EH - FFFEH)

 

 

Message Terminator

FFFFH

 

 

Example

The goal is to read the eight bytes of data from the tag starting at address 1. A timeout of 2 seconds (07D0H = 2000 x 1 ms increments) is set for the completion of the Read.

Command From Host

MSB

LSB

Remarks

AAH

05H

Perform Command 5

 

 

 

00H

01H

Start Byte Address = 0001H

 

 

 

00H

08H

Read Length = 8 bytes

 

 

 

07H

D0H

2-second Timeout

 

 

 

FFH

FFH

Message Terminator

 

 

 

Response from Controller

MSB

LSB

Remarks

AAH

05H

Command Echo

 

 

 

00H

52H

Read Data 1 =52H

 

 

 

00H

46H

Read Data 2 =46H

 

 

 

00H

49H

Read Data 3 =49H

 

 

 

00H

44H

Read Data 4 =44H

 

 

 

00H

20H

Read Data 5 =20H

 

 

 

00H

54H

Read Data 6 =54H

 

 

 

00H

61H

Read Data 7 =61H

 

 

 

00H

67H

Read Data 8 =67H

 

 

 

FFH

FFH

Message Terminator

 

 

 

61

LRP2000 Passive Reader/Writer

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Escort LRP2000 manual ABxS Command 05H Read, Response from Controller