Chapter
3
Reference Manual
Ruler E
Configuring the Ruler
External Triggering
There are two ways to trigger the Ruler using external signals:
Enable
Triggers the Ruler to start measuring a series of profiles. This signal
could for example come from a photo switch located along the con-
veyor belt.
This signal is connected to In1 on the Power I/O connector.
Pulse triggering
Triggers the Ruler to measure one profile. This signal could for exam-
ple be the differential signals Phase 1 and Phase 2 coming from an
encoder on the conveyor belt.
This signal is connected to In1 and In2 on the Encoder connector.
The Ruler is configured to use these external signals for triggering by setting the
Enable
and
Trig mode
parameters.
When using
enable
, you set the
Scan height
parameter to specify the number of meas-
urements that the Ruler should make after the Enable signal goes high. After the specified
number of measurements, the Ruler checks the enable signal again, and if it is high
continues to make another series of measurements.
When using
pulse triggering
, you set the
Number of pulses per trig
parameter to specify
the number of pulses on the signal before a measurement is made. The Ruler counts the
number of pulses received on the pulse triggering inputs using an internal counter, which
is reset every time a measurement is made.
When you connect both In1 and In2 on the Ruler’s Encoder connector to signals from the
encoder, the signal on In2 can be used for detecting when the object moves backwards. If
so, the Ruler will decrement the counter instead. This way the object can move backward
and forward under the Ruler, but the Ruler will not measure any section of the object more
than once.
Figure 3.2 – Using In1 and In2 to detect movements in both directions.
The pulse triggering counter will also be reset every time the Enable signal goes high.
If pulse triggering is not used, the Ruler will measure in
free-running
mode, make meas-
urements with a regular time interval determined by cycle time. The distance on the object
between two measurements is then determined by the speed of the object – that is, how
far the object has moved during that time.
To find the actual distance between two measurements when measuring in free-running
mode, you can connect an encoder to the Ruler and set the
Mark
parameter. This will
make the Ruler embed the encoder information in the profiles sent to the PC.
Forward Backward Forward
In1
(pulse trig)
In2
(direction)
Increment
No. of
pulses
per trig
Decrement Increment
Pulse trig
counter
Profiles
16
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