Balluff BIS U-6026-034-104-06-ST35 Betriebsanleitung Seite 79

BIS U-6026-034-1_4-06-ST35
Processor unit
8
Device function (continued)
If the selected data carrier is not in the field of the antenna
at the moment, the Select command is processed without
errors anyway, but following read/write commands return
an error with status code 01
hex
If the selected data carrier identifier is present on multiple
data carriers, the following commands are run as follows:
– Read commands are run on one data carrier, which is
randomly selected from the suitable data carriers.
– Write commands are run on all suitable data carriers.
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(no data carrier).
Notes
– The data carrier identifier is usually taken from
a preceding command 47
hex
data carriers (EPC). Omit the leading fill bytes
in the data carrier list for this. The entire entry
is usually used for the 12-byte EPC format;
for the 64-byte format (as ASCII digits in byte
address 0 and 1 of the respective entry), read
the actual length and then read out the
identifier starting from the byte address
(64-length).
Example: Length specification = "24" means
that the EPC is in byte address 40...63.
– If multiple data carriers are to be processed in
sequence, what usually results is the following
command sequence:
Command 47 : Read multiple data carriers
hex
(EPC)
Command 40 : Select (1st identifier)
hex
... Process 1st data carrier
Command 40 : Select (2nd identifier)
hex
... Process 2nd data carrier
Command 40 : Select (3rd identifier)
hex
... Process 3rd data carrier
etc.
Command 41 : Unselect
hex
The controller can choose the sequence of
data carriers at random, omit data carriers or
select the same one repeatedly.
– With the BIS U-602_ devices the selection is
made only using the EPC, thereby also
enabling operation of multiple antennas at
one read position. Then a data carrier with a
suitable data carrier identifier is also read if it
is located in front of an antenna other than
the one to which the Select command refers.
If you need to ensure that only data carriers in
front of the current antenna are read after a
Select command, the EPC identifiers of the
data carrier must be unique and the presence
of the data carrier in front of the desired
antenna must first be checked using
command 47 : Read multiple data carriers
hex
(EPC).
– A data carrier selection for an antenna
remains valid until one of the following events
occurs:
– A new selection is defined.
– An Unselect command undoes the
selection.
– The GR bit (basic state) for the
corresponding antenna is set.
– The device is restarted.
english
: Read multiple
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