Functions
Leuze electronic
MLD 300, MLD 500
20
4.7
Muting
By means of muting, the protective function can be temporarily and properly suppressed, e.g. if objects
are to be transported through the protective field. During this time, the OSSDs remain in the ON state in
spite of interruption of one or more beams.
Muting is only initiated automatically and via two mutually independent muting signals. The muting indi
-
cator illuminates continuously during the entire duration of muting operation. End of muting operation is
forced as soon as the preset maximum duration (muting timeout) is exceeded.
Following malfunctions or operationally related interruptions (e.g. power failure, violation of the concur
-
rency condition during timing controlled 2-sensor muting on activation of the muting sensors), the system
can be manually reset with the start/restart button and overridden.
4.7.1 Timing controlled 2-sensor muting
The two muting sensors MS1 and MS2 are arranged in such a way that the beams cross and the process
can automatically activate both sensors (within 4 s). As a result, an object can be transported through the
protective field in both directions. The intersection point must be within the danger zone to prevent muting
from being unintentionally triggered.
If muting was properly activated, it remains active even during brief interruptions of a single sensor signal.
On foil-wrapped objects, for example, brief signal interruptions can occur—particularly with light scanners.
These short signal interruptions are, therefore, filtered out for up to max. 3 s (MLD 335, MLD 535: 300 ms).
If both muting sensors are inactive simultaneously, timing controlled 2-sensor muting ends.
Figure 4.1: Reaction of the OSSD switching output of the MLD 312 to an external test request
For series connection of multiple type 2 devices (e.g. MLD 312 and type 2 Light Beam Safety
Devices), cross connection between test signal and switching output is to be avoided. For this
purpose, connecting cables must be laid so that no cross connections can occur, or test signal
and switching output must be laid in separate cables.
max.150 ms
high-impedance
OSSD-24 V
high-impedance or 0 V
Input + 24 V
6 ms
6 ms
1
Danger zone
MS1 Muting sensor 1
MS2 Muting sensor 2
t
Time frame in which both muting sensors must be activated (4 s)
Figure 4.2: Timing controlled 2-sensor muting–arrangement of
the muting sensors and timing
t
MS1
MS2
MS1
MS2
Muting
1
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