PAGE Acquisition Mode

In the PAGE acquisition mode, a unique acquisition sequence can be executed within the Channel activity period.

The PAGE acquisition sequence is composed of a repetitive sequence of PAGE acquisition phases. Each PAGE acquisition phase is responsible for the image capture of one object.

Each page is constituted of contiguous lines; the page length, expressed in lines, is specified by PageLength_Ln.

A single sequence is capable to acquire SeqLength_Pg pages within the channel activity period.

The PAGE acquisition mode is explicitly invoked by assigning value PAGE to AcquisitionMode.

The first action is to define all MultiCam Channel parameters before channel activation.

More specifically the following acquisition control parameters need to be configured:

Parameter	Value range
AcquisitionMode	PAGE
TrigMode	IMMEDIATE, HARD, SOFT and COMBINED
NextTrigMode	SAME, REPEAT, HARD, SOFT and COMBINED
BreakEffect	FINISH, ABORT
PageLength_Ln	1 ~ 65535
SeqLength_Pg	MC_INDETERMINATE, 1 ~ 65535

When invoking the PAGE acquisition mode:

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The ActivityLength parameter is enforced to 1. The channel goes inactive at the completion of the sequence.

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The PhaseLength_Pg parameter is enforced to 1. A single page is acquired during an acquisition phase.

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The page length can be enforced by setting PageLength_Ln to any value up to 65,535. For more information see Setting Optimal Page Length.

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TrigMode establishes the starting condition of the sequence and consequently the starting condition of the first phase —the first PAGE— of the sequence. Possible values are IMMEDIATE, HARD, SOFT and COMBINED. The default MultiCam setting is COMBINED.

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NextTrigMode establishes the starting condition of the subsequent phases —pages— within the sequence. Possible values areSAME, REPEAT, HARD, SOFT and COMBINED. The default value is SAME.

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The sequence length is specified by SeqLength_Pg. Assigning a value MC_INDETERMINATE enforces an indefinite PAGE acquisition sequence. Assigning any value ≥ 1 enforces a finite PAGE acquisition sequence.

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EndTrigMode is enforced to AUTO. The sequence terminates automatically after the acquisition of the specified number of pages. An indefinite acquisition sequence stops when the channel is forced to its inactive state.

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BreakEffect establishes the effect of a user break on the channel. When set to FINISH, it ensures the integrity of the last acquired phase —page—– even when the user break event occurs during its execution; this is the default value. When set to ABORT, the effect of the user break is immediate (at line boundary); the current acquisition might be incomplete; the portion of image already acquired is available.

Setting ChannelState parameter to ACTIVE activates the channel and arms the trigger circuit.

The PAGE acquisition sequence will effectively start after the first trigger event occurring after channel activation when the first acquisition phase is triggered.

The trigger source is determined by the Start Trigger condition. Usually, the start trigger event is a hard trigger; however a soft trigger signal can also be selected. Usually, the trigger is derived from a position detector. The trigger condition is defined by parameter TrigMode.

A programmable page delay can optionally be specified with parameter PageDelay_Ln. It compensates a trigger advance delivered by a position detector placed away from the camera field of view.

To summarize the usage of trigger parameters, see Hardware Trigger.

At first trigger event, the object scanning starts effectively; a "Start of Sequence" signal is reported to the user.

The trigger source for all subsequent acquisition phases is determined by the Next Start Trigger condition. Usually, the Next start trigger event is the same as the Start Trigger condition. The next trigger condition is defined by parameter NextTrigMode.

To summarize the usage of trigger parameters, see Hardware Trigger.

A programmable page delay can optionally be specified with parameter PageDelay_Ln. It compensates a trigger advance delivered by a position detector placed away from the camera field of view.

At subsequent trigger events, the object scanning starts effectively; however no "Start of Sequence" signal is reported to the user.

Once the PAGE acquisition phase is started, the frame grabber acquires data lines and stores them into one surface.

Destination surface receives an arbitrary number of lines as defined by parameter PageLength_Ln.

Parameter LineIndex reflects the number of lines already written in a partially filled surface. If SeqLength_Ln is not a multiple of PageLength_Ln, the surface will be partially filled. A new surface is selected at each begin of Page acquisition phase.

Lines are acquired at a rate defined by the line trigger condition. When object speed is variable, it is convenient to generate a line trigger derived from a motion encoder.

For more information, see Line Trigger and Line-Scan Synchronization.

Within a PAGE acquisition sequence, the acquisition phase stops automatically when the surface is filled after the acquisition of PageLength_Ln lines.

The PAGE acquisition sequence supports objects up to highest possible value of PageLength_Ln, namely 65,535 lines. For large objects, consider using the LONGPAGE acquisition mode.

When acquisition phase is stopped, a "Surface filled" signal is reported immediately to the user. The "Surface filled" signal will be reported as soon as all the acquired data lines are transferred to the host memory.

The PAGE acquisition mode allows two methods to stop the sequence: Manual stop and Automatic stop.

If the number of scanned objects is known before starting the sequence and is not higher than 65,535, the automatic stop method can be used to automatically stop the sequence after a predefined number of pages. This variant of PAGE acquisition is named Finite PAGE acquisition. In this case, the number of pages to be acquired needs to be specified before Channel activation.

If the number of scanned objects is unknown or higher than 65,535, the manual stop method is required. In this case, the parameter SeqLength_Pg should be set to MC_INDETERMINATE, in order to define an infinite PAGE acquisition sequence.

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Elapsed_Pg reports the number of acquired pages in the sequence.

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When the sequence length is defined (SeqLength_Pg≠MC_INDETERMINATE), Remaining_Pg reports the number of remaining pages in the sequence.