Siemens SIMATIC Ident Function Manual page 30

Configuring the instructions
4.5 Programming add-on instructions
Special features of the RF68xR reader
Note that the length of the data buffer ("IDENT_DATA") must correspond to at least the
length of the maximum expected data. If more transponders are identified and data read out
than have space in the assigned buffer length of "IDENT_DATA", the data of these
transponders is lost. This reaction is indicated by the error "0xE7FE0400" (buffer overflow).
The "DURATION" and "DUR_UNIT" parameters are also available for the RF68xR reader.
Using the parameters, you can specify the duration of the inventories.
With the readers. there are four different modes that you can select with the "ATTRIBUTE"
parameter.
● At the start, a certain duration/number (period of time, number of inventories, number of
"Observed" events or identified transponders) is specified. A distinction is made between
the following options:
– Duration
– Number of inventories
– Number of "Observed" events
Inventories are then taken by the reader for this time or number of inventories. When the
specified time/number is reached, the instruction is ended and returns all identified
transponders in "IDENT_DATA". In other words, other commands can only be executed
when all inventories have been taken completely. The unit (time or number) is specified
using "DUR_UNIT" and the value (time value or number) using "DURATION". This mode
can be executed using the attributes "0x80" and "0x81". Depending on the attribute, more
or less data is supplied about the identified transponders.
● With the attributes "0x86" (start "Presence_Mode") and "0x87" (end "Presence_Mode"),
inventories can be taken permanently. The presence of a transponder can then always
be queried using "PRESENCE" without having to start the "Inventory" instruction with
"EXECUTE". No information about the identified transponders is returned when the
command executes!
To obtain information about the identified transponders, use one of the two calls listed
above (with time / number of inventories = 0).
When this mode is active, commands relating to transponders are not executed
immediately but only when a transponder is identified. This achieves shorter reaction
times since the command is already pending when the transponder enters the antenna
field.
"Presence_Mode" is practical in the context of the "Repeat command" function.
The "NUMBER_TAGS" output parameter is used to output the number of identified
transponders. With the attributes "0x80" and "0x81" on completion of the read operation, the
sum of all identified transponders is displayed. With the attribute "0x86" the number of
currently identified transponders is shown at the "NUMBER_TAGS" output parameter (max.
15),without having to start the "Inventory" instruction with "EXECUTE".
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Take inventories for a specified period of time
Take a specified number of inventories
Take inventories until a specified number of transponders have been identified at the
same time.
Ident profile, Add-on instruction for Rockwell systems
Function Manual, 01/2019, C79000-G8976-C410-03