Escort LRP2000 manual ABxS Command 08H Tag Search, ABxS Command 0DH Stop/Start Continuous Read

RFID Communications

6.4.5 ABxS Command 08H: Tag Search

DESCRIPTION

Check to see if there is an RFID tag in the antenna field.

DISCUSSION

This command activates the controller to search for the presence of a tag within range of the antenna. If the controller finds a tag, it returns a command echo to the host. The timeout value is given in 1 ms increments and can have a value of 001EH to FFFEH (30 to 65,534 ms). When the timeout is set to 0, the controller returns a syntax error. If no tag is present, it returns an error message. See Section 6.2 for more information on error codes.

Field	Remarks
Command	Command number in hex preceded by AAH
Timeout	Timeout value given in 1 ms units (001EH - FFFEH)
Message Terminator	FFFFH

Example

Checks for an RFID tag in the RF field. A timeout of 2 seconds (07D0H = 2000 x 1 ms increments) is set for the completion of the Tag Search.

Command from Host

MSB	LSB	Remarks
AAH	08H	Perform Command 8
07H	D0H	2-second Timeout
FFH	FFH	Message Terminator

Response from Controller

MSB	LSB	Remarks
AAH	08H	Command Echo
FFH	FFH	Message Terminator

6.4.6 ABxS Command 0DH: Stop/Start Continuous Read

DESCRIPTION

When in Continuous Read mode, the controller sends read commands continuously to any tag in range of the antenna. When a tag comes within range, it is read and the data passed to the host computer. The controller continues to read the tag but does not send the same data to the host until the tag has been outside the RF field for a specified time period. This Delay Between Identical Decodes parameter prevents redundant data transmissions when the controller is in Continuous Read mode.

DISCUSSION

The Start/Stop Continuous Read command contains three parameters: read length, start address, and delay between identical decodes. The read length parameter switches the mode. Any valid, non-zero length (1-48) sets the controller into Continuous Read mode. A read length value of 00H turns Continuous Mode off. The Delay Between Identical Decodes parameters can have a value of 0 to 60 seconds. When the Delay Between Identical Decodes is set to 0, the controller continuously reads AND transmits tag data to the host. This can flood the buffers and cause communication errors and data loss. If the controller receives other commands from the host, it executes them and then resumes Continuous Read mode. To exit Continuous Read mode, issue the command with a read length of 0.

LRP2000 Passive Reader/Writer 64