User's Manual

V740 RFID READER/WRITER, ANTENNA 2005-07, REV.01
OPERATION MANUAL
26 of 45 ©OMRON CORPORATION 2005
• To query EPC0 tags:
• To query a specific sub class of tags, given a
range of tag ID values:
When the client software reads tags of the 'EPC0'
protocol, it should indicate 'read_count>1' in the
'where_specification'.
SELECT id FROM tag_id WHERE
protocol_id='EPC1' AND
tag_id>=min_tag_id AND
tag_id<=max_tag_id;
For example, the command is as follows:
The reader returns the tag ID values for all the
present tags between min_tag_id and
max_tag_id, which are hexadecimal values.
SELECT id FROM tag_id WHERE
antenna_id=1 AND protocol_id='EPC0' AND
read_count>1;
To read EPC1 and EPC0 tags at the same time:
• To query tags by specific or all antennas:
SELECT id FROM tag_id WHERE
protocol_id='EPC1' OR
(protocol_id='EPC0' AND read_count>1);
SELECT id FROM tag_id WHERE
antenna_id=1 AND protocol_id='EPC1';
SELECT id FROM tag_id WHERE
protocol_id='EPC1';
Note: If you don't specify the 'read_count>1', the
reader returns ghost data occasionally. 'Ghost
data' means the data which is returned even if
tags do not exist in the antenna field.
At the first, the reader searches tags only by
antenna 1. Second the reader searches tags by
all antennas available. Omitting the antenna
indication in the 'where_specification' means to
search all antennas available.
• To query during a specific time:
SELECT id FROM tag_id WHERE
antenna_id=1 AND protocol_id='EPC1'
SET time_out=500;
Note: When specifying multiple antennas even if
an antenna that does not exist is specified, the
reader obtains the tag ID only using antenna 1
and doesn't return any an error message.
The command imposes a time out constraint of
500ms; i.e., the reader stops reading and returns
all collected data after 500ms. The order in which
specifying arguments are used is irrelevant. The
default timeout is 250ms if none is specified.
SELECT id FROM tag_id WHERE
(antenna_id=1 OR antenna_id=5) AND
protocol_id='EPC1';
It is important to always use a timeout in
specifying a query to achieve optimal
performance for a given application. Detailed
information will be discussed in the next section
• The client software can specify multiple entries in
the select_list field of the SELECT command:
SELECT id, antenna_id FROM tag_id
WHERE antenna_id=1 AND
protocol_id='EPC1';
Timeout
SELECT protocol_id, timestamp, id,
antenna_id FROM tag_id WHERE
antenna_id=1 AND protocol_id='EPC1';
The client software can impose a time limit on a read
operation, requesting the reader to search only for a
limited time (specified in milliseconds). The reader
may fail to detect some tags if insufficient time is
allocated to the search operation. The time_out is the
parameter used for specifying the time allocated for
the read operation.
The first example returns the tag IDs and
antenna_ids, and the second returns protocol_ids
and the time that the tag was read (seconds from
the unix epoch, Jan 1, 1970) with the tag IDs and
antennas_ids.
Note: To read timestamp, the NTP sever must be
set up in advance.
The reader returns protocol_id as an integer value.
The value '1' represents 'EPC1',and the value '9'
represents 'EPC0'. For example, the query with
protocol_id and the response is as follows:
In general, a large time_out should be used for dock
stations (>2000ms), and short time_outs should be
used for conveyor belts (<100ms).
Dock
Station
Conveyor
Application
short
time out
long
[Query] SELECT protocol_id, id FROM
tag_id WHERE antenna_id=1 AND
protocol_id='EPC1';
[Res] 1|0xCE791111111111111111<LF><LF>
SELECT id FROM tag_id SET time_out=1000;