X64 Xcelera-HS PX8 User's Manual
X64 Xcelera-HS PX8 Reference
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K
D
D
K
D
D
K
D
D
K
D
D
K
D
D
Shaft Encoder phase A
Shaft Encoder phase B
K = Keep
D = Drop or Skip
Note: in this example, Number of trigger to drop = 2
Line acquired
Figure 20: Encoder Input with Pulse-drop Counter
Note that camera file parameters are best modified by using the Sapera CamExpert program.
Example using Sequential Encoder Input
Support of a dual phase encoder should consider the direction of motion of one phase signal to the
other. Such a case might exist where system vibrations and/or conveyor backlash can cause the
encoder to briefly travel backwards. The acquisition device must in those cases count the reverse
steps and subtract the forward steps such that only pulses after the reverse count reaches zero are
considered. By using the event “Shaft Encoder Reverse Counter Overflow”, an application can
monitor an overflow of this counter. Also, if one wants to trigger a camera at its maximum line rate
using a high jitter shaft encoder, the parameter CORACQ_PRM_LINE_TRIGGER_AUTO_DELAY can
be used to delay automatically line triggers to the camera to avoid over-triggering a camera, and
thus not miss a line. Note that some cameras integrate this feature. See also the event “Line
Trigger Too Fast” that can be enabled when using the ‘auto delay’ feature.
The example figure below shows shaft encoder signals with high jitter. If the acquisition is
triggered when phase B follows phase A, with jitter present phase B may precede phase A. Use of
the Shaft Encoder Direction parameter will prevent false trigger conditions.
Shaft Encoder phase A
Shaft Encoder phase B
Figure 21: Using Shaft Encoder Direction Parameter
Note: Modify camera file parameters easily with the Sapera CamExpert program.
