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V740 RFID READER ANTENNA
NOTE. SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE. REV. 1.1
OPERATION MANUAL
18 of 27
© OMRON CORPORATION 2004
event (‘\n’) if tags matching the WHERE clause
are not present. The first version requests a read
from a specific antenna, while the second does
not. The second 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 if none is
specified is 250ms.
Any previous statement’s use of the
time_out
variable will change the default timeout until a
RESET
is asserted
. It is important to always use
a timeout in specifying a query to achieve optimal
performance for a given application. This will be
discussed later in section
•
To query a specific sub class of tags, given a
range of
ePC
s:
SELECT id FROM tag_id WHERE
tag_id>min_tag_id AND
tag_id<max_tag_id SET timeout=1000;
The Reader returns the
ePC
s for all the present
tags between
id_min
and
id_max
, which are
hexadecimal values.
•
To query all tags:
SELECT id FROM tag_id SET
timeout=2500;
SELECT id FROM tag_id WHERE
antenna_id=1 SET timeout=2500;
The Reader returns all the tags it can find. The
second version requests a read from a specific
antenna, while the first does not.
•
The client software specifies which information it
requires in the
select_list
field of the
SELECT command:
SELECT id, antenna_id FROM tag_id SET
timeout=2500;
SELECT frequency, timestamp, id,
antenna_id FROM tag_id SET
time_out=1000;
Returns the id and antenna_id of every tag in the
field in the first example and the frequency and
time the tag was read at (seconds from the unix
epoch, Jan 1, 1970) in the second example.
Update, Where
The UPDATE command is to write new data into a
table. This can be used to write a new tag_id or sleep
the Reader for a specified amount of time. The
structure of an UPDATE command is as follows:
UPDATE
table
SET col=
expression
[,
…] [WHERE
wherelist
];
table
and
col
entries are provided in Table 1.
The WHERE clause is specified in the same manner
as in the SELECT call above. In the following we
provide some examples for usage of
UPDATE
:
•
To write data for a 64-bit ePC tag id with a
specified lock code, password and block_number:
UPDATE tag_data SET
data=0xFEDCBA9876543210,
block_number=0, lock_code=0xef,
password=0xcd WHERE protocol=’CC915’
AND antenna_id=1;
The Reader returns the tag_id if the write
operation was successful or “
Error 128:
Error encountered while attempting to
process tags\n\n
” in safe mode, and "
Error
128: Error encountered while
attempting to process tags\n\n
" in
single query mode otherwise.
•
To write for a specified amount of time:
UPDATE tag_data SET
data=0xFEDCBA9876543210,
block_number=1, lock_code=0xef,
password=0xcd, time_out=250 WHERE
protocol=’CC915’ AND antenna_id=1;
Would try to write the tag id for 250ms.
•
To sleep the Reader for a specified amount of
time:
UPDATE sleep SET time_out=500;
Would turn off the RF interface for 500ms. This
can be useful for scheduling Readers and
reducing interference.
•
Other
Updates:
kill, locking, password
UPDATE tag_id SET killed=1,
id=0x112233445566778899AABBCC,passwor
d=0x88 WHERE protocol_id='EPC1' AND
antenna_id=4;
UPDATE tag_id SET locked=1,
id=0x0123456789ABCDEF WHERE
protocol_id='EPC1' AND antenna_id=4;
UPDATE tag_id SET password=0x88,
id=0x0123456789ABCDEF WHERE
protocol_id='EPC1' AND antenna_id=4;
Cursors
The client software has the ability to declare cursors
(saved queries), which it can then use to request data
repeatedly using the OPEN or the AUTO_MODE
command. A maximum of 16 cursors can be defined.
To create a cursor: