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2.2.2 General Observations,
Commands, and Syntax
We note that a reader behaves very much like
database wherein each individual tag represents an
entry in the database with a given set of attributes.
Due to memory constraints of the reader, the system
will remove entries from the database as they are
queried.
The syntax for querying against this database is
derived from SQL syntax.
In the simplest case, the client software explicitly
requests data by polling the readers. The request
protocol is implemented in such a way that the client
software specifies:
Required information.
• What subset of tags the reader should consider.
• Which read constraints should be applied.
Example commands:
•
SELECT id FROM tag_id WHERE
id=0x1234567890ABCDEF AND antenna_id=1 AND
protocol_id='EPC1';
Would return a tag only if its tag ID was
0x1234567890ABCDEF
•
SELECT id FROM tag_id WHERE (antenna_id=1
OR antenna_id=2) AND protocol_id='EPC1'
SET time_out=1000;
Would return a tag only if the antenna ID was 1 or
2 and will search for at least 1000ms.
Note: The RQL command is terminated by a
semicolon. When you use sample commands in this
manual, you must input a command in one line
without line feed characters.
V740 RFID READER/WRITER, ANTENNA
OPERATION MANUAL
.
2.2.3 Extended RQL Command
Structure supported by the V740
Reader
Extended Command Set for Data and Write,
and Lock operations
ID Read : Identify tags, including anti-collision.
ID Write : Change tag ID
ID Lock : Prevent further changes of tag ID
Kill : Initialize tag
Password : Set a pass-code to kill a tag
Table1: Supported Protocols for each function
Function
ID
Kill
Password
With the exception of the 'ID Read' command, all
commands are protocol and antenna specific and can
only be used with a single protocol at a time and with
a single antenna at a time. Hence all queries with the
exception 'ID Read' need to be constrained to one
protocol and one antenna, for example
WHERE protocol_id='EPC1' and
antenna_id=1
A complete example of an 'ID Write' query would be
UPDATE tag_id SET
id=0x0123456789ABCDEF WHERE
protocol_id='EPC1' AND antenna_id=1.
'ID Read' (enumerate tags) is, by definition, a multi-
target command, since it determines what the
individual targets are in the first place.
There are some special cases to the single-target rule.
For example, ID Write is semantically tricky – what
does it mean to target a tag if its target ID is going to
be changing? In the current state of the art, most
protocols do not support addressed ID writes (ID write
targets all tag IDs) or disallow tag ID changes entirely.
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EPC1
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Read
○
Write
Lock
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©OMRON CORPORATION 2005
EPC1B
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2005-09, REV0.1
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