BackwardMotionCancellationMode

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Description

Type	Enumerated
Description
"Set" effect
"Get" effect

Classification

Class	Channel
Category	Encoder Control
Level	Adjust

Identifiers

String	BackwardMotionCancellationMode
C, C++	MC_BackwardMotionCancellationMode
.NET	MC.BackwardMotionCancellationMode
Numerical	10352

The backward cancellation circuit stops sending line trigger pulses as soon as a backward motion is detected. If such an event occurs, the acquisition is stopped.

When the backward cancellation control is configured in the FILTER mode (F-mode), the line acquisition resumes as soon as the motion is again in the forward direction. Therefore, the cancellation circuit filters out all the pulses corresponding to the backward direction.

When the backward cancellation control is configured in the COMPENSATE mode (C-mode), the line acquisition resumes when the motion is again in the forward direction at the place it was interrupted. Therefore, the cancellation circuit filters out not only the pulses corresponding to the backward direction, but a number of forward pulses equal to the number of skipped backward pulses.

In C-Mode, the cancellation circuit uses a "backward pulse counter" that:

Increments by 1 every clock in the backward direction
Decrements by 1 every clock in the forward direction until it reaches 0
Resets at the beginning of each MultiCam acquisition sequence, more precisely, at the first trigger event of the sequence. This trigger is considered as the reference for the position along the web for the whole acquisition sequence.

In C-Mode, all pulses occurring when the counter value is different of zero are blocked.

The counter has a 16-bit span; backward displacement up to 65535 pulses can be compensated.

The backward cancellation circuit operates exclusively with quadrature lotion encoders.

The FILTERED and COMPENSATE values are authorized only when LineRateMode=PULSE and LineTrigCtl=DIFF_PAIRED or ISO_PAIRED (the line trigger source is configured for a quadrature encoder).

Note. Considering that the rate converter circuit operates only in a limited range of line rates and certainly not for the low rates, MultiCam prevents the application using the backward motion cancellation circuit when LineRateMode=CONVERT.

Possible values

Name	Identifier	Description
OFF	MC_BackwardMotionCancellationMode_OFF	Disables the backward motion cancellation circuit. Default value.
FILTERED	MC_BackwardMotionCancellationMode_FILTERED	Enables the backward motion cancellation circuit. Selects the filter mode: ignore encoder pulses during backward motion.
COMPENSATE	MC_BackwardMotionCancellationMode_COMPENSATE	Enables the backward motion cancellation circuit. Selects the compensate-Mode: ignore encoder pulses during backward motion and resume acquisition in the forward direction at the place it was interrupted.