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56 • Xtium-CL MX4 Reference Xtium-CL MX4 User's Manual

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 a maximum line rate camera trigger source is a high jitter shaft encoder, the parameter

CORACQ_PRM_LINE_TRIGGER_AUTO_DELAY can be used to automatically delay line triggers 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 16: Using Shaft Encoder Direction Parameter

Note: Modify camera file parameters easily with the Sapera CamExpert program.

CVI/CCF File Parameters Used

Shaft Encoder Enable = X, where:

• If X = 1, Shaft Encoder is enabled

• If X = 0, Shaft Encoder is disabled

Shaft Encoder Pulse Drop = X, where:

• X = number of trigger pulses ignored between valid triggers

Shaft Encoder Pulse Multiply = X, where:

• X = number of trigger pulses generated for each shaft encoder pulses

Shaft Encoder Pulse Drop/Multiply Order = X, where:

• If X = 1, the drop operation will be done first, followed by the multiplier operation

• If X = 0 or 2, the multiplier operation will be done first, followed by the drop operation

Shaft Encoder Direction = X, where:

• X = 0, Ignore direction

• X = 1, Forward steps are detected by pulse order A/B (forward motion)

• X = 2, Forward steps are detected by pulse order B/A (reverse motion)

Note: For information on camera configuration files, see the Sapera Acquisition Parameters

Reference Manual (OC-SAPM-APR00).

Dalsa Xtium-CL MX4 User Manual

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