Siemens SIMATIC RF600 Series Configuration Manual page 236

Application examples
12.3 Filtering out transponders detected due to overshoot
Requirement
The read points are mounted, equipped and aligned.
Note that this example is only of practical use when the reader searches for transponders for
a defined period. This is controlled by a light barrier which for example triggers a trigger
"IO_LEVEL" or "IO_EDGE" or by parameter assignment of the period of an inventory
command.
Parameter assignment
Follow the steps below to ensure that the transponders identified due to overshoot are
filtered out.
1. With the menu item "Diagnostics - Tag monitor" determine the RSSI values of the
identified transponders of the read point involved.
Based on the RSSI values you can determine when transponders are identified due to
overshoot. Transponders identified due to overshoot normally have significantly poorer
RSSI values than transponders located in the regular antenna field.
2. With the antenna parameters "RSSI threshold" and "Input attenuation" contained in the
menu item "Settings - Read point" and the algorithm "Smoothing" filter out the
transponders identified due to overshoot.
3. Check your settings using the menu item "Diagnostics - Tag monitor".
The "RSSI delta" algorithm
As an alternative to the antenna parameters named above, you can also use the algorithm
"RSSI delta". When using this algorithm, you must, however, remember the following points:
● This algorithm is only useful for applications that use time-limited inventories.
● Transponders found to be valid once, must remain valid for the remaining time. To do this
in "Smoothing" the value of "Lost Count" must be set to the maximum value "65535".
● The evaluation of which transponders are valid, may only take place at the end of the
taking of inventories.
For this reason we recommend to limit overshoots first with the antenna parameters and
algorithms listed above.
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Configuration Manual, 11/2018, C79000-G8976-C386-07
SIMATIC RF600