Siemens SIMATIC RF650R Configuration Manual page 49

Parameter
Input attenuation
Polarization
Algorithms
Compared with other frequency bands (LF, HF), UHF RFID has the following special
properties:
● Large distances in the range of several meters,
● Reflection of the waves on metal surfaces,
● Region-dependent bandwidth restricted by regulations
In conjunction with the fact that electromagnetic waves in the UHF range are not visible, this
often leads to unwanted or incomprehensible responses in UHF systems. Typical, simple
examples include:
● Not everything is read or even nothing is read.
● Reading works but writing does not.
● Transponders are identified that should not be identified at all.
There are often simple explanations for these responses and therefore usually also
solutions. Algorithms are additional functions that help you to achieve the required
functionality even in difficult radio conditions. The following environmental conditions are
possible causes of this response:
● There are several readers in a restricted space, e.g. every 3 to 5 meters along a
production line (high reader density).
● The objects to be identified or the transponders are close together (the distance from
each other is less than the antenna field).
● There is a lot of metal in the environment (e.g. production environment with metallic
conveyor technology, loading doors with metal ramps)
● The objects to be identified are on a metal surface.
SIMATIC RF650R/RF680R/RF685R
Configuration Manual, 10/2015, C79000-G8976-C386-03
Description
The input attenuation weakens the strength of received transponder signals at
the reader input. Increasing the attenuation means that received weak tran-
sponder signals are no longer identified by the reader. This attenuation applies
both to transponder responses as well as to signals of neighboring readers.
Adapting this parameter helps to reduce disruptions caused by neighboring
readers and transponder populations.
Value range
Increment
The polarization indicates the alignment of the waves of the antenna and de-
pends on the antenna being used. Most antennas have an unchangeable
polarization.
The polarization of the internal antenna of the RF685R reader can be set. If
you use the internal antenna of the RF685R reader, you also need to enable
the required polarization using the corresponding check box. If more than one
check box is selected, the polarization is changed with each inventory. This
increases the probability of identification in difficult radio conditions but does,
however, increase the access time (time required for the additional invento-
ries).
Configuring with the WBM
6.3 The menu items of the WBM
0 ... 31.75 dB
0.25 dB
49