Basler SCOUT LIGHT User Manual download pdf (Page 70)

Image Acquisition Control

62 Basler scout light

6.9 Acquisition Timing Chart

Figure 25 shows a timing chart for image acquisition and transmission. The chart assumes that

exposure is triggered with an ExTrig signal with rising edge activation and that the camera is set for

programmable exposure mode.

As Figure 25 shows, there is a slight delay between the rise of the ExTrig signal and the start of

exposure. After the exposure time for an image capture is complete, the camera begins reading out

the captured image data from the imaging sensor into a buffer in the camera. When the camera has

determined that a sufficient amount of image data has accumulated in the buffer, it will begin

transmitting the data from the camera to the host PC.

This buffering technique avoids the need to exactly synchronize the clock used for sensor readout

with the clock used for data transmission over the IEEE 1394b bus. The camera will begin

transmitting data when it has determined that it can safely do so without over-running or under-

running the buffer. This buffering technique is also an important element in achieving the highest

possible frame rate with the best image quality.

The exposure start delay is the amount of time between the point where the trigger signal

transitions to the point where exposure actually begins.

The frame readout time is the amount of time it takes to read out the data for a captured image

from the CCD sensor into the image buffer.

The time to transmission end is the amount of time between the point where the camera begins

reading out the captured image data from the sensor to the point where it finishes transmitting the

data for the captured image from the buffer to the host PC.

The exposure start delay varies from camera model to camera model. The table below shows the

exposure start delay for each camera model:

Note that, if the debouncer feature is used, the debouncer setting for the input line must be added

to the exposure start delays shown in Table 10 to determine the total start delay. For example,

assume that you are using an slA1000-30fm camera and that you have set the cameras for

hardware triggering. Also assume that you have selected input line 1 to accept the hardware trigger

signal and that you have set the Line Debouncer Time Abs parameter for input line 1 to 5 µs. In this

case:

Total Start Delay = Start Delay from Table 10+ Debouncer Setting

Total Start Delay = 45.33 µs+ 5 µs

Camera Model Exposure Start Delay

slA750-60fm 180.0 µs

slA1000-30fm 45.33 µs

slA1390-17fm 58.90 µs

slA1600-14fm 60.52 µs

Table 10: Exposure Start Delays

1 2 ... 65 66 67 68 69 70 71 72 73 74 75 ... 165 166

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Basler SCOUT LIGHT User Manual Page 70