Chapter
1
Reference Manual
Ruler E
Overview
1.4
Triggering
The Ruler can be triggered by external signals in two different ways:
Enable
Triggers the Ruler to start measuring a series of profiles.
As long as
the Enable signal is low, the Ruler will not measure anything. This sig-
nal could for example come from a photo switch located along the
conveyor belt.
The Enable signal is also useful for synchronizing two or more Rulers.
Pulse triggering
Triggers the Ruler to measure one profile. This signal could for exam-
ple come from an encoder on the conveyor belt.
Figure 1.8 – Triggering the Ruler with Enable and Pulse triggering signals.
The Ruler must be configured to use these external signals for triggering. This is done by
setting the
Enable
and
Trig mode
parameters with Ranger Studio.
If pulse triggering is not used for triggering profiles, the Ruler will measure in
free-running
mode – that is, make measurements with a regular time interval determined by the Ruler’s
cycle time. The actual distance on the object between two profiles is then determined by
the speed of the object – that is, how far the object has moved during that time.
When measuring the true shape of an object, you should always use an encoder with the
Ruler. With the signals from the encoder as pulse triggering signals, it is guaranteed that
the distance that the object has moved between two profiles is well known.
You can find the actual distance between two profiles even if the Ruler is measuring in
free-running mode, as long as you have an encoder connected to the Ruler. The encoder
information can then be embedded in the profiles sent to the PC, where your application
can use this information to calculate the distance.
Enable
Profiles
Pulse
triggering
12
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