Detecting overtriggering

Introduction

The image acquisition of a camera consists of two steps:

• exposure of the sensor and
• readout of the sensor data

During these steps, a trigger signal will be skipped (a.k.a. overtrigger):

Figure 1: Trigger counter increases but the start exposure counter not

To notice overtriggering, there are 2 possibilities. Either use

• counters or
  • Counter1 counts the incoming trigger signals, the
  • Counter2 counts the ExposureStart signals.
• FrameTriggerMissed in EventControl

Using ImpactControlCenter and 2 Counters

First of all, we have to set the trigger in "Setting → Base → Camera → GenICam → Acquisition Control" with following settings:

Property name ImpactControlCenter	Setting
Trigger Selector	FrameStart
Trigger Mode	On
Trigger Source	Line4
Trigger Activation	RisingEdge
Exposure Mode	Timed

This trigger will start an acquisition after a rising edge signal on line 4 (= DigIn0 ).

Now, set the two counters. Both counters (Counter1 and Counter2) will be reset and start after the acquisition (AcquisitionStart) has started.

While Counter1 increases with every ExposureStart event (see figure above for the event and acquisition details) ...

Figure 2: Setting Counter1

... Counter2 increases with every RisingEdge of the trigger signal:

Figure 3: Setting Counter2

Now, you can check if the trigger signal is skipped (when a rising edge signal is active during readout) or not by comparing the two counters.

Enable the inclusion of the selected chunk data ("Chunk Mode Active = 1") in the payload of the image in "Setting → Base → Camera → GenICam → Chunk Data Control":

Figure 4: Enable chunk data

Activate the info overlay in the display area. Right-click on the live display and select: "Request Info Overlay"

Figure 5: Show chunk data

The following figure shows that no trigger signal is skipped:

Figure 6: Trigger Signal counter equals ExposureStart counter

The following figure shows that the acquisition is overtriggered:

Figure 7: Trigger Signal counter is higher than ExposureStart counter

Using ImpactControlCenter and EventControl

Since

Firmware version 2.53.0

The event FrameTriggerMissed occurs when trigger signals are detected while the sensor is not ready for the next image.

For this, choose FrameTriggerMissed in the "Setting → Base → Camera → GenICam → Event Control → Event Selector" and activate it by setting the EventNotification to On:

Figure 8: EventControl - FrameTriggerMissed

As soon as the selected Event occurs, the info will be displayed in the Event Control section.

Note

Only one event per readout is possible, even if there is more than one missed trigger.