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 |
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Start Address | Tag address where the read starts |
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Read Length | Number of tag addresses to be read |
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Timeout | Timeout value given in 1 ms units (001EH - FFFEH) |
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Message Terminator | FFFFH |
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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 |
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00H | 01H | Start Byte Address = 0001H |
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00H | 08H | Read Length = 8 bytes |
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07H | D0H | |
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FFH | FFH | Message Terminator |
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Response from Controller
MSB | LSB | Remarks |
AAH | 05H | Command Echo |
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00H | 52H | Read Data 1 =52H |
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00H | 46H | Read Data 2 =46H |
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00H | 49H | Read Data 3 =49H |
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00H | 44H | Read Data 4 =44H |
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00H | 20H | Read Data 5 =20H |
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00H | 54H | Read Data 6 =54H |
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00H | 61H | Read Data 7 =61H |
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00H | 67H | Read Data 8 =67H |
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FFH | FFH | Message Terminator |
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61 | LRP2000 Passive Reader/Writer |