Anti-Tampering Functions: Anti-Masking; Masking Signal; Environment Memorization Process; Causes Of Masking - Leuze electronic LBK SBV Original Operating Instructions

5 Functioning principles
5.11 Anti-tampering functions: anti-masking
5.11.1

Masking signal

The sensor detects the presence of objects that could obstruct the field of view. When the system
configuration is saved, the sensor memorizes the surrounding environment. If the sensor subsequently
detects variations in the environment that could influence the field of view, it sends a masking signal to the
controller. The sensor monitors from -50° to 50° on the horizontal plane regardless of the angular coverage
set. Upon receiving a masking signal, the controller deactivates the safety outputs.
Note: the masking signal is not guaranteed in the presence of objects which cause reflection effects that
bring their RCS below the minimum detectable threshold.
5.11.2

Environment memorization process

The sensor starts the surrounding environment memorization process when the LBK Designer application
configuration is saved. From that moment, it waits for the system to exit the alarm status and for the scene
to be static up to 20 seconds, then scans and memorizes the environment.
NOTICE
If the scene is not static during the 20 seconds interval, the system remains in a fault status
(Signal error) and the system configuration must be saved again.
It is recommended to start the memorization process after at least 3 minutes from turning on the system to
guarantee that the sensor has reached the operating temperature.
Only at the conclusion of the memorization process it is possible for the sensor to send masking signals.
5.11.3

Causes of masking

Possible causes of masking signals are the following:
An object that obstructs the field of view of the sensor has been placed in the detection field.
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The environment in the detection field changes significantly, for example, if the sensor is installed on
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moving parts or if there are moving parts inside of the detection field.
The configuration was saved with sensors installed in an environment that is different from the working
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environment.
There were temperature fluctuations.
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5.11.4

Masking signal when the system is turned on

If the system was off for several hours and there were temperature fluctuations, the sensor might send a
false masking signal when it is turned on. The safety outputs activate automatically within 3 minutes when
the sensor reaches its working temperature. This does not happen if this temperature is still very far from
the reference temperature.
5.11.5

Settings

For each sensor, the anti-masking settings are the following:
maximum distance from the sensor (range [20 cm/7.87 in, 100 cm/3.28 ft], 10 cm/3.94 in steps) in which
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the function is active
sensitivity
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These are the four levels of sensitivity:
Note: the function has a tolerance area where the actual detection of a masking object depends on the RCS
of the object and on the sensitivity level set. The high sensitivity level has the largest area, about 10-20 cm
(3.94-7.87 in).
Leuze electronic GmbH + Co. KG Sensor LBK SBV 50