7
Relay output
N.A. contact
PNP static output Output voltage
Material sensed
(Beam occupied)
ON
HIGH
Material not sensed
(Raggio libero)
OFF
LOW
Table 1
Muting sensors output.
Using photoelectric sensors, this condition is assured using the crossed
beam technique. An example in which two photoelectric reflex switches
are used as muting sensors is shown in figure 1 below.
Figure 1
Positioning of the safety barrier and of the muting sensors.
For correct functioning of the system:
F
The material must obscure the two muting beams at the sameThe material must obscure the two muting beams at the same
time (within 4 seconds) before intercepting the light barrier;time (within 4 seconds) before intercepting the light barrier;
F
An operator must NOT obscure the two muting beams at theAn operator must NOT obscure the two muting beams at the
same time (within 4 seconds) before intercepting the lightsame time (within 4 seconds) before intercepting the light
barrier.barrier.
These conditions are guaranteed only in the case of correct reciprocal
positioning of the sensors and light barrier, taking into account the
dimensions and feed speed of the pallet and the response times of the
sensing devices (fig. 2, page 7).
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