RFID Communications
6.4.10 ABxS Command 82H: SN Read All
DESCRIPTION
Command 82H reads the serial numbers and the specified bytes of data from all RFID tags in the field or those with the specified Family ID. Returns the serial number of the tags read, along with tag data.
DISCUSSION
This command is used to read segments of data from contiguous areas of tag memory. It is capable of transferring the entire read/write address of data transferred to the host with one command. 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 response to this command contains the serial number of the responding tags preceding the data from those tags. The termination packet is transmitted when the timeout expires. Each packet is sent to the host as soon as it is available. The returned serial numbers can be used to read and write to tags in the field via the SN Read/Write command.
The SN Read All consists of Family ID, Reserved Byte, a start address and length, followed by a timeout value, and the message terminator, FFFFH. A special termination packet is sent when the timeout expires. If the read length exceeds the last tag address, the controller returns a syntax error, code 21H.
Field | Remarks |
Command | Command number in hex preceded by AAH |
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Tag Family | Tag Family ID - 00H = all tags |
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Reserved | 00H |
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Start Address | Tag address where the read will start |
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Read Length | Numbers 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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LRP2000 Passive Reader/Writer | 68 |