Command Repetition - Siemens SIMATIC Ident Function Manual

3.2.3

Command repetition

Operating principle
After a new start (or init_run) of the CM, FB 45 transfers the command (or command chain)
once to the CM. Command transmission is automatic with the first command_start. This
command (or the last command or the command chain) always remains buffered on the CM.
If command repetition is started now, the command buffered on the CM is executed again,
and the result(s) transferred to FB 45.
Advantages of command repetition
● The data transfer on PROFIBUS/PROFINET is minimized. This is particularly noticeable
● The CM processes each tag independent of FB 45. In concrete terms, this means each
● Total data throughput is increased considerably particularly with controllers which have
Command overview for use with command repetition
Command [hex]
normal chained*
01 41
02 42
03 43
04 44
08 48
0A 4A
0B 4B
*) Chained commands are not supported by all readers. You should also note the
information in the relevant system manual.
FB 45 for MOBY U, MOBY D, RF200, RF300
Function Manual, 07/2012, J31069-D0166-U001-A4-7618
with extensive bus configurations and slow (bus) transmission speeds.
tag is processed even in applications with a very fast sequence of tags. This takes place
no matter what the (PROFI) BUS speed.
few system resources for non-cyclic frames.
Syntax
WRITE
READ
INIT
SLG STATUS
END
SET-ANT
MDS-STATUS
Command
Description
Write data to transponder
Read data from transponder
Initialize transponder
Query reader status
END; terminate communication
with the transponder
Switch antenna on/off
Query transponder status
Parameterizing
3.2 RFID commands
Permitted with
command repetition
yes; but only with identical write
data
yes
yes
No
yes
No
yes
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