Device description
Leuze electronic
LES 36
25
TNT
35/7-2
4
V
Note!
In PROFIBUS operation, cascading only functions as described above via the
InTrig
and
OutCas
inputs/outputs at X1. In this case, the maximum detection rate of 100Hz is achieved.
Make certain, however, that the input data of the PROFIBUS light section sensors are still
transmitted in the same bus cycle; monitor the scan numbers if necessary.
Alternatively, light section sensors with PROFIBUS can be selectively triggered in sequence.
Master output 'uTrigger' of the sensor to be triggered is incremented on each PLC cycle;
the master outputs of the other sensors do not change. The maximum detection rate of
100Hz is not achieved with this process.
If multiple sensors are triggered in a PROFIBUS cycle, mutual interference may occur
between the sensors if they are in the same visual field and the time between updating byte
'uTrigger' is shorter than the maximum exposure time (Exposure Time) of 1.3ms.
4.3
Measurement functions:
LES
With the LES, you can reliably detect objects and measure their edge position, height and
width. Adaptation of the LES to an application is performed using the LESsoft configuration
software. All settings for the application are made there and stored in up to 16 inspection
tasks.
Functional principle of object and edge detection with the LES
The distance profile of the application is determined along the laser line in 376 measurement
points. Rectangular analysis windows, used for object and edge detection, can be defined
in the measurement range.
Object detection:
The number of measurement points is counted in the analysis window (Analysis Window
= AW or Edge Analysis Window = EAW) and compared with two adjustable limits. From this,
the logical state
ok
or
not ok
of the analysis window is determined. For unique object detec-
tion, it may be necessary to combine multiple analysis windows. For this purpose, the LES
offers the AND combination and inversion of multiple analysis windows. The logic combi-
nations ensure the detection of problematic objects.
Edge detection:
Windows for edge detection are called Edge Analysis Windows (EAW). In an EAW, object
detection can be performed as described above. Also determined in an EAW are the X and
Z coordinates of the first ("left-most") and the last ("right-most") measurement point. By
appropriately selecting the size and position of the EAWs, it is possible to determine coor-
dinates of edge positions. From these, the width and height of an object are calculated. For
robust edge detection, the "Sequent Hits" parameter was introduced. The minimum number
of measurement points set there must occur in succession in the EAW to detect a valid edge.
Outliers or missing measurement points reset the counter.
