Trigger Ready Signal - Basler A101f User Manual

Operation and Features

3.3 Trigger Ready Signal

The trigger ready signal is not defined in the 1394 Trade Association Digital Camera
Specification. Trigger ready is a special feature of Basler cameras.
One possible way to control the camera is to perform an image exposure followed by charge read
out and frame transfer and to wait until frame transfer is complete before beginning the next
exposure. This situation is illustrated in Figure 3-5.
Frame 1
Exposure
Frame 1 Transfer
Read
Out
Figure 3-5: Exposure Between Frame Transfers
While the method of control shown above may be useful in many situations, it is not workable if
your objective is to achieve maximum frame rate. To achieve maximum frame rate, most of the
exposure for each frame must take place while the previous frame is being transferred out of the
CCD array. This situation is illustrated in Figure 3-6.
Frame 1
Exposure
Read
Out
Figure 3-6: Exposure During Frame Transfer
A point to notice when looking at Figure 3-6 is that exposure must not end during frame transfer;
the end of exposure for the next frame must occur at least 100 ns after the transfer of the current
frame. (For example, the exposure for frame two must end at least 100 ns after frame one transfer
is complete.)
This situation poses a problem when you are controlling exposure with an ExTrig signal, that is,
how will you know when to toggle the ExTrig signal and begin exposure so that the exposure will
end at least 100 ns after the last frame transfer.
This problem is addressed by the trigger ready signal. The trigger ready signal will go high at the
earliest moment that you can begin exposure and still be sure that the exposure will end at least
100 ns after the transfer of the last frame.
3-8
DRAFT
Frame 2
Exposure
Read
Out
Frame 2
Exposure
Frame 1 Transfer Frame 2 Transfer
> 100 ns
Read
Out
Frame 3
Exposure
Frame 2 Transfer
Frame 3
Exposure
Frame 3 Transfer
> 100 ns
Read
Out
Frame 3 Transfer
Read
Out
Frame 4
Exposure
> 100 ns
Read
Out
BASLER A101
f