Basler slA1000-30fm, User Manual, Page: 27 / 166

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 .