AW00118508000 Acquisition Control
Basler racer Camera Link 64
6.1.5 Using a Hardware Line Start Trigger Signal
6.1.5.1 Introduction
If the TriggerMode parameter for the line start trigger is set to On and the TriggerSource parameter
is set to CC1, CC2, CC3, or CC4, an externally generated electrical signal injected into the selected
source will act as the line start trigger signal for the camera. This type of trigger signal is generally
referred to as a hardware trigger signal or as an external line start trigger signal (ExLSTrig signal).
A rising edge or a falling edge of the ExLSTrig signal can be used to trigger line acquisition. The
TriggerActivation parameter is used to select rising edge or falling edge triggering.
Assuming that the camera is in a "waiting for line start trigger" acquisition status, line acquisition will
start when the hardware line start trigger signal is received by the camera.
When the camera receives a hardware trigger signal and begins exposure, it will exit the "waiting
for line start trigger" acquisition status because at that point, it cannot react to a new line start trigger
signal. As soon as the camera is capable of reacting to a new line start trigger signal, it will
automatically return to the "waiting for line start trigger" acquisition status.
When the camera is operating under control of an ExLSTrig signal, the period of the ExLSTrig signal
will determine the rate at which the camera will acquire lines:
For example, if you are operating a camera with an ExLSTrig signal period of 20 ms (0.020 s):
So in this case, the line rate is 50 lps.
If you have selected CC1, CC2, CC3, or CC4 as the trigger source, your frame grabber will typically
apply the electrical signal to the selected input via the Camera Link cable. For more information
about applying an ExLSTrig signal to CC1, CC2, CC3, or CC4, see the documentation for your
frame grabber.
For more information about determining the maximum allowed line rate with the current camera
settings, see Section 6.4 on page 87.
If you are triggering line acquisition with an ExLSTrig signal and you attempt to
acquire lines at too high a rate, some of the line trigger signals that you apply will
be received by the camera when it is not in a "waiting for line start trigger"
acquisition status. The camera will ignore any line start trigger signals that it
receives when it is not "waiting for line start trigger". (This situation is commonly
referred to as "overtriggering" the camera.)
To avoid overtriggering, you should not attempt to acquire lines at a rate that
exceeds the maximum allowed with the current camera settings.
1
ExLSTrig period in seconds
------------------------------------------------------------------------- Line Rate=
1
0.020
---------------50 lps=
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