Device description
24
Technical description LES
Leuze electronic
PROFIBUS trigger
So that a measurement can be triggered on each PROFIBUS cycle, the PROFIBUS trigger
of the LES responds to a change of master output byte
uTrigger
. The control only needs
to increment the trigger value in order to initiate a new measurement.
The maximum trigger frequency is 100Hz. If triggering occurs during a measurement, the
trigger signal is ignored, as is the case in the
Free Running
operating mode.
4.2.4
Cascading
Figure 4.5:
Cascading application example
If several light section sensors are operated,
there is the risk of mutual interference if the
reflected laser beam of one sensor can be
received by the receiver of another sensor at
the time of reading.
This can easily be seen in figure 4.5. Here
three light section sensors are used to deter-
mine the log thickness reliably from all sides.
To prevent mutual interference the light
section sensors can be operated cascaded:
the exposure by the second sensor will be initiated following completion of the exposure
by the first sensor. To achieve this, the cascading output of the first sensor must be
connected to the trigger input of the second sensor. Up to 6 sensors can thus be operated
cascaded.
Trigger settings
Sensor 1, or the master, can be operated in this case both triggered as well as continuously.
All other sensors must be operated triggered.
Cascading settings
For all sensors except the last slave, the cascading output must be enabled via configuration
software:
Cascading Output: Enable
.
Laser
Measurement value output
Trigger input, pin 5 at X1 /
not required
Cascading output,
pin 6 at X1
Sensor 1 / Master
Laser
Measurement value output
Trigger input, pin 5 at X1
Cascading output,
pin 6 at X1
Sensor 2 / 1. slave
Laser
Measurement value output
Trigger input, pin 5 at X1
Cascading output,
pin 6 at X1
Sensor 3 / 2. slave
Figure 4.4:
Signal sequence for cascading
