Free-running
The camera will acquire 2D images (in Areascan mode) or profiles
(in Linescan3D mode) with a regular time interval. In Areascan
mode the time interval is controlled by the
AcquisitionFrameRate
parameter and in Linescan3D mode by the
AcquisitionLineRate
parameter.
When the acquisition of profiles is free-running, the distance
between two profiles varies if the speed of the object is not con‐
stant. This may distort the image. To avoid distortion, you can use
an encoder and record the counter value for each profile. This
information makes it possible to calculate a correct image.
2D image
triggering
The camera will acquire 2D images based on external pulses on
the encoder inputs.
The use of a four-phase encoder allows tracking of different
motion patterns. The principles for motion tracking during 2D
image triggering are the same as for line triggering,
ing using an encoder", page 33
.
7.11.3
Triggering using an encoder
When you use an encoder for triggering, the camera counts the number of pulses
received on the encoder inputs using an internal counter. When the specified number
of pulses have been received, a profile or a 2D image is triggered and the camera
resets the triggering condition counter.
Four-phase (dual-channel) encoder
The default definition of a pulse is a full four-phase cycle on the encoder inputs. This
gives a pulse counter that is robust to jitter and noise on the inputs.
A four-phase encoder can handle movements in both directions (forward and back‐
ward). The camera can be configured to react to the pulses in different ways, resulting
in different ways to trigger profiles. The different line triggering modes are illustrated
below.
Mode
Parameter
Description
Position
EncoderOut‐
putMode
=
PositionUp
or Position‐
Down
The encoder triggers a profile for each object position.
If the object has moved backward, no profiles are triggered until
the object has moved (at least) an equal distance forward.
PositionUp: "Forward" is defined as the positive direction.
PositionDown: "Forward" is defined as the negative direction.
Direction
EncoderOut‐
putMode
=
DirectionUp
or Direction‐
Down
The encoder triggers profiles when the object is moving forward.
If the object has moved backward, new profiles will be triggered as
soon as the object moves forward again.
DirectionUp: "Forward" is defined as the positive direction.
DirectionDown: "Forward" is defined as the negative direction.
Motion
EncoderOut‐
putMode
=
Motion
The encoder triggers profiles when the object is moving either
backward or forward.
Table 6: Triggering modes
1
3
2
Position
Direction
CONFIGURATION
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8020774/14IM/2019-07 | SICK
O P E R A T I N G I N S T R U C T I O N S | Ranger3
33
Subject to change without notice