Basler SCOUT LIGHT User Manual download pdf (Page 27)

Functional Description

Basler scout light 19

4 Functional Description

This section provides an overview of the camera’s functionality from a system perspective. The

overview will aid your understanding when you read the more detailed information included in the

next chapters of the user’s manual.

4.1 Overview (All Models Except slA750-60fm)

Each camera provides features such as a full frame shutter and electronic exposure time control.

Exposure start, exposure time, and charge readout can be controlled by parameters transmitted to

the camera via the Basler pylon API and the IEEE 1394b interface. There are also parameters

available to set the camera for single frame acquisition or continuous frame acquisition.

Exposure start can also be controlled via an externally generated hardware trigger (ExTrig) signal.

The ExTrig signal facilitates periodic or non-periodic acquisition start. Modes are available that

allow the length of exposure time to be directly controlled by the ExTrig signal or to be set for a pre-

programmed period of time.

Accumulated charges are read out of the sensor when exposure ends. At readout, accumulated

charges are transported from the sensor’s light-sensitive elements (pixels) to the vertical shift

registers (see Figure 6 on page 20). The charges from the bottom line of pixels in the array are then

moved into a horizontal shift register. Next, the charges are shifted out of the horizontal register. As

the charges move out of the horizontal shift register, they are converted to voltages proportional to

the size of each charge. Each voltage is then amplified by a Variable Gain Control (VGC) and

digitized by an Analog-to-Digital converter (ADC). After each voltage has been amplified and

digitized, it passes through an FPGA and into an image buffer. All shifting is clocked according to

the camera’s internal data rate. Shifting continues in a linewise fashion until all image data has been

read out of the sensor.

The pixel data leaves the image buffer and passes back through the FPGA to an IEEE1394b link

layer controller where it is assembled into data packets. The packets are passed to a 1394b

physical layer controller which transmits them isochronously to an interface board in the host PC.

The physical and link layer controllers also handle transmission and receipt of asynchronous control

data such as changes to the camera’s parameters.

The image buffer between the sensor and the link layer controller allows data to be read out of the

sensor at a rate that is independent of the data transmission rate between the camera and the host

computer. This ensures that the data transmission rate has no influence on image quality.

Note

The information in this section applies to all camera models except the

slA750-60fm. For information about slA750-60fm cameras, see Section 4.2 on

page 21.

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Basler SCOUT LIGHT User Manual Page 27