Idiomas disponibles
Idiomas disponibles
OPERATING INSTRUCTIONS
3.5.2
Absence of reference object or reference surface
en
14
O P E R A T I N G I N S T R U C T I O N S | WTT12-S
For this safety-related function, the sensor is used to detect the absence of a reference
object or a reference surface and provide a defined switching signal depending on the
situation present. The corresponding output signal can then be used by a downstream
controller to put the application into a safe state (e.g., stopping a vehicle).
L
L
L
Figure 6: Absence of an object
Sensor
1
Light beam
2
Background
3
"Test" switching threshold
L
1
Teach-in point
L
2
"Operation" switching threshold
L
3
The sensor needs to be taught-in to a reference surface (teach point L
The thresholds for the "Operation" and "Test" modes are derived from a defined offset,
see "Data sheet", page
30:
•
Positive offset for "Operation"
•
Negative offset for "Test"
This ensures a reliable and rugged use of the safety sensor.
In "Operation" mode, the output should switch to ACTIVE if the measured distance is
equal to or less than L
, i.e., the reference surface is detected. If the reference object
3
or reference surface is absent, the sensor switches to INACTIVE (measured value > L
This represents the safety-related state.
The device can be switched between operating mode and test mode via a test input. In
test mode, the threshold value is shifted to L
now recognized as absent. The safety function is thereby requested and checked for the
correct response.
In test mode, the output should switch to INACTIVE if the measured distance is between
L
and L
.
1
3
The following table shows the different states depending on the measured distance
(L
) and based on the set threshold (L
meas
Table 2: States depending on the measured distance at the set threshold
Distance
L
< L
meas
1
L
≤ L
≤ L
1
meas
3
L
> L
meas
3
2
L
L
L
so that the actual reference surface is
1
or L
).
1
3
Operation (L
threshold)
3
Active
Active
Inactive
1
3
).
2
).
3
Test (L
threshold)
1
Active
Inactive
Inactive
8029123/2024/01/15 | SICK
Subject to change without notice
