Escort LRP2000 manual ABxF Command 8DH Stop/Start Continuous Read All, 113

RFID Communications

6.5.17 ABxF Command 8DH: Stop/Start Continuous Read All

DESCRIPTION

Command 8DH starts and stops continuous read mode for multiple tags.

DISCUSSION

The Start/Stop Continuous Read All mode is initiated by issuing the command with the Number of Bytes set to any valid nonzero value. Stop the mode by sending the command with a read length of 0. While in this mode, any other command can be issued and will be handled properly. After processing the new command, the controller resumes the Continuous Read All mode.

The command has a parameter, Tag Repeat Count, that can prevent multiple reads of the same tag. A tag is not read a second time until a specified number of tags have been read since the tag was last read. Allowed values are from 0 up to 255 (FFH), where 0 means the tag can be re-read anytime. When Continuous Read All mode is interrupted with other commands, the tag delay count is cleared during execution of the other commands and then resumed. When the continuous read mode resumes, all previously read tags will be read again. The controller responds with an acknowledge packet followed by data packets for each tag read. The CONFIG LED blinks after each packet transmission.

Field	Content
Header	0202H
Command Size	Command length in bytes excluding the header command size, checksum, and terminator bytes.
Command	8DH
Family ID	Tag Family ID - 00H = all tags
Reserved	Ignored byte, set to 00H
Start Address	Tag address for the start of the read
Number of Bytes	0 = stop. Any valid nonzero value indicates the number of bytes to be read
Tag Repeat Count	Number of tags that must be read before the same tag is read again (0-255)
Checksum	Optional checksum
Message Terminator	03H

Example

Reads four bytes of data from the tag starting at address 0001H. The Family ID byte is set to zero, so all tags are read. The tag repeat count is set to 20 (14H). Two tags respond with read data.

Command from Host

Field	Content
Header	0202H
Command Size	0008H
Command Code	8DH
Family ID	00H
Reserved	00H
Start Address	0001H
Read Length	0004H
Tag Repeat Count	14H
Checksum	50H
Terminator	03H

Response from Controller

Field	Content
Header	0202H
Response Size	0001H
Command Echo	8DH
Checksum	71H
Terminator	03H

113 LRP2000 Passive Reader/Writer