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  4. VCXG double shutter
VT_Timing_Double_Shutter.png

This example describes how to program a sequencer for a double shutter triggered via a hardware trigger. A double shutter aims to deliver 2 images in a very short timeframe. It uses a special technique to acquire the second image while the first image is still read out of the camera.

If you want to know more about what to do with a sequencer or when to use a double shutter please refer to the application notes below and the user-guide of your camera.

The figure shows the resulting double shot as signal curves: Avoiding extraneous light (grey shaded area in the exposure signal) during the last part of the 2nd exposure leads to the desired camera behavior.

    // STOP AUQISITION AND LOAD DEFAULT PARAMETERS
pDevice->GetRemoteNode("AcquisitionStop")->Execute();
pDevice->GetRemoteNode("UserSetSelector")->SetString("Default");
pDevice->GetRemoteNode("UserSetLoad")->Execute();

// CONFIGURE HARDWARE TRIGGER INPUT
// this needs to be done before the sequencer is configured
pDevice->GetRemoteNode("TriggerMode")->SetString("On");
pDevice->GetRemoteNode("TriggerSource")->SetString("Line0");
pDevice->GetRemoteNode("TriggerActivation")->SetString("RisingEdge");
pDevice->GetRemoteNode("TriggerDelay")->SetDouble(0.0);
pDevice->GetRemoteNode("LineSelector")->SetString("Line0");
pDevice->GetRemoteNode("LineInverter")->SetBool(false);
pDevice->GetRemoteNode("LineDebouncerHighTimeAbs")->SetDouble(1.0);
pDevice->GetRemoteNode("LineDebouncerLowTimeAbs")->SetDouble(1.0);

// CONFIGURE TIMER FOR FLASH
// the timer is started on each exposure start for a duration of 100 µsec
pDevice->GetRemoteNode("TimerSelector")->SetString("Timer1");
pDevice->GetRemoteNode("TimerTriggerSource")->SetString("ExposureStart");
pDevice->GetRemoteNode("TimerTriggerActivation")->SetString("RisingEdge");
pDevice->GetRemoteNode("TimerDelay")->SetDouble(0.0);
// TimerDuration (of Flash) equals Set0 ExposureTime below
pDevice->GetRemoteNode("TimerDuration")->SetDouble(100.0); //100.0 µsec

// CONFIGURE GPIO “Line3” FOR FLASH CONTROL
pDevice->GetRemoteNode("LineSelector")->SetString("Line3");
pDevice->GetRemoteNode("LineSource")->SetString("Timer1Active"); // Line3 is high while Timer1 set up before is active
pDevice->GetRemoteNode("LineInverter")->SetBool(false);




// SWITCH TO SEQUENCER CONFIG MODE
pDevice->GetRemoteNode("SequencerConfigurationMode")->SetString("On");

// SET 0 (FIRST STEP OF THE SEQUENCE)
pDevice->GetRemoteNode("SequencerSetSelector")->SetInt(0);
pDevice->GetRemoteNode("SequencerSetLoad")->Execute();

pDevice->GetRemoteNode("TriggerMode")->SetString("On");
pDevice->GetRemoteNode("OffsetX")->SetInt(0);
pDevice->GetRemoteNode("OffsetY")->SetInt(0);
pDevice->GetRemoteNode("Width")->SetInt(320);
pDevice->GetRemoteNode("Height")->SetInt(240);
pDevice->GetRemoteNode("OffsetX")->SetInt(160);
pDevice->GetRemoteNode("OffsetY")->SetInt(120);
// ExposureTime of Set0 = TimerDuration (of Flash)
pDevice->GetRemoteNode("ExposureTime")->SetDouble(100.0); // 100 µsec

pDevice->GetRemoteNode("SequencerPathSelector")->SetInt(0);
pDevice->GetRemoteNode("SequencerTriggerSource")->SetString("ExposureActive");
pDevice->GetRemoteNode("SequencerTriggerActivation")->SetString("RisingEdge");
// next sequencer step will be Set1 set up below
pDevice->GetRemoteNode("SequencerSetNext")->SetInt(1);

pDevice->GetRemoteNode("SequencerSetSave")->Execute();

// SET 1 (SECOND STEP OF THE SEQUENCE)
pDevice->GetRemoteNode("SequencerSetSelector")->SetInt(1);
pDevice->GetRemoteNode("SequencerSetLoad")->Execute();
// the TriggerMode is set to Off, otherwise the camera would wait for the next hardware trigger which is not desired. Changing TriggerMode to Off will return the camera to free run mode, after one exposure we will be back in Set0 where the TriggerMode is switched On again in order for the camera to wait for the next hardware trigger.
pDevice->GetRemoteNode("TriggerMode")->SetString("Off");
pDevice->GetRemoteNode("OffsetX")->SetInt(0);
pDevice->GetRemoteNode("OffsetY")->SetInt(0);
pDevice->GetRemoteNode("Width")->SetInt(320);
pDevice->GetRemoteNode("Height")->SetInt(240);
pDevice->GetRemoteNode("OffsetX")->SetInt(160);
pDevice->GetRemoteNode("OffsetY")->SetInt(120);
// here is the Double Shutter trick, for this second exposure we set the exposure time to 
// the same time as the ReadOutTime of the first image (as calculated by the camera). The 
// camera will recognize that the second image will be ready for ReadOut only after the 
// ReadOut of the first image is finished and therefore start the exposure straight away 
// instead of waiting for the first image to finish ReadOut
bo_double fReadOutTime_Set1 = (bo_double)pDevice->GetRemoteNode("ReadOutTime")->GetInt();
pDevice->GetRemoteNode("ExposureTime")->SetDouble(fReadOutTime_Set1);
pDevice->GetRemoteNode("SequencerPathSelector")->SetInt(0);
pDevice->GetRemoteNode("SequencerTriggerSource")->SetString("ExposureActive");
pDevice->GetRemoteNode("SequencerTriggerActivation")->SetString("RisingEdge");
// next sequencer step will be Step0 again
pDevice->GetRemoteNode("SequencerSetNext")->SetInt(0);
pDevice->GetRemoteNode("SequencerSetSave")->Execute();
// Start with the Set0
pDevice->GetRemoteNode("SequencerSetStart")->SetInt(0);

// SEQUENCER CONFIG END
pDevice->GetRemoteNode("SequencerConfigurationMode")->SetString("Off");



// START CAMERA SEQUENCER
pDevice->GetRemoteNode("SequencerMode")->SetString("On");
pDataStream->StartAcquisitionContinuous();
pDevice->GetRemoteNode("AcquisitionStart")->Execute();

// CAPTURE IMAGES

// STOP CAMERA SEQUENCER
pDevice->GetRemoteNode("AcquisitionStop")->Execute();
pDataStream->StopAcquisition();
pDevice->GetRemoteNode("SequencerMode")->SetString("Off"); 
  
    // STOP AUQISITION AND LOAD DEFAULT PARAMETERS
mDevice.RemoteNodeList["AcquisitionStop"].Execute();
mDevice.RemoteNodeList["UserSetSelector"].Value = "Default";
mDevice.RemoteNodeList["UserSetLoad"].Execute();

// CONFIGURE HARDWARE TRIGGER INPUT
// this needs to be done before the sequencer is configured
mDevice.RemoteNodeList["TriggerMode"].Value = "On";
mDevice.RemoteNodeList["TriggerSource"].Value = "Line0";
mDevice.RemoteNodeList["TriggerActivation"].Value = "RisingEdge";
mDevice.RemoteNodeList["TriggerDelay"].Value = (double)0.0;
mDevice.RemoteNodeList["LineSelector"].Value = "Line0";
mDevice.RemoteNodeList["LineInverter"].Value = false;
mDevice.RemoteNodeList["LineDebouncerHighTimeAbs"].Value = (double)1.0;
mDevice.RemoteNodeList["LineDebouncerLowTimeAbs"].Value = (double)1.0;

// CONFIGURE TIMER FOR FLASH
// the timer is started on each exposure start for a duration of 100 µsec
mDevice.RemoteNodeList["TimerSelector"].Value = "Timer1";
mDevice.RemoteNodeList["TimerTriggerSource"].Value = "ExposureStart";
mDevice.RemoteNodeList["TimerTriggerActivation"].Value = "RisingEdge";
mDevice.RemoteNodeList["TimerDelay"].Value = (double)0.0;
// TimerDuration (of Flash) equals Set0 ExposureTime below
mDevice.RemoteNodeList["TimerDuration"].Value = (double)100.0; //100.0 µsec

// CONFIGURE GPIO “Line3” FOR FLASH CONTROL
mDevice.RemoteNodeList["LineSelector"].Value = "Line3";
mDevice.RemoteNodeList["LineSource"].Value = "Timer1Active"; // Line3 is high while Timer1 set up before is active
mDevice.RemoteNodeList["LineInverter"].Value = false;

// SWITCH TO SEQUENCER CONFIG MODE
mDevice.RemoteNodeList["SequencerConfigurationMode"].Value = "On";

// SET 0 (FIRST STEP OF THE SEQUENCE)
mDevice.RemoteNodeList["SequencerSetSelector"].Value = (long)0;
mDevice.RemoteNodeList["SequencerSetLoad"].Execute();

mDevice.RemoteNodeList["TriggerMode"].Value = "On";
mDevice.RemoteNodeList["OffsetX"].Value = (long)0;
mDevice.RemoteNodeList["OffsetY"].Value = (long)0;
mDevice.RemoteNodeList["Width"].Value = (long)320;
mDevice.RemoteNodeList["Height"].Value = (long)240;
mDevice.RemoteNodeList["OffsetX"].Value = (long)160;
mDevice.RemoteNodeList["OffsetY"].Value = (long)120;
// ExposureTime of Set0 = TimerDuration (of Flash)
mDevice.RemoteNodeList["ExposureTime"].Value = (double)100.0; // 100 µsec

mDevice.RemoteNodeList["SequencerPathSelector"].Value = (long)0;
mDevice.RemoteNodeList["SequencerTriggerSource"].Value = "ExposureActive";
mDevice.RemoteNodeList["SequencerTriggerActivation"].Value = "RisingEdge";
// next sequencer step will be Set1 set up below
mDevice.RemoteNodeList["SequencerSetNext"].Value = (long)1;

mDevice.RemoteNodeList["SequencerSetSave"].Execute();

// SET 1 (SECOND STEP OF THE SEQUENCE)
mDevice.RemoteNodeList["SequencerSetSelector"].Value = (long)1;
mDevice.RemoteNodeList["SequencerSetLoad"].Execute();
// the TriggerMode is set to Off, otherwise the camera would wait for the next hardware trigger which is not desired. Changing TriggerMode to Off will return the camera to free run mode, after one exposure we will be back in Set0 where the TriggerMode is switched On again in order for the camera to wait for the next hardware trigger.
mDevice.RemoteNodeList["TriggerMode"].Value = "Off";
mDevice.RemoteNodeList["OffsetX"].Value = (long)0;
mDevice.RemoteNodeList["OffsetY"].Value = (long)0;
mDevice.RemoteNodeList["Width"].Value = (long)320;
mDevice.RemoteNodeList["Height"].Value = (long)240;
mDevice.RemoteNodeList["OffsetX"].Value = (long)160;
mDevice.RemoteNodeList["OffsetY"].Value = (long)120;
// here is the Double Shutter trick, for this second exposure we set the exposure time to 
// the same time as the ReadOutTime of the first image(as calculated by the camera). The 
// camera will recognize that the second image will be ready for ReadOut only after the 
// ReadOut of the first image is finished and therefore start the exposure straight away 
// instead of waiting for the first image to finish ReadOut
double fReadOutTime_Set1 = (double)((long)mDevice.RemoteNodeList["ReadOutTime"].Value);
mDevice.RemoteNodeList["ExposureTime"].Value = (double)fReadOutTime_Set1;

mDevice.RemoteNodeList["SequencerPathSelector"].Value = (long)0;
mDevice.RemoteNodeList["SequencerTriggerSource"].Value = "ExposureActive";
mDevice.RemoteNodeList["SequencerTriggerActivation"].Value = "RisingEdge";
// Next sequencer step will be Step0 again
mDevice.RemoteNodeList["SequencerSetNext"].Value = (long)0;
mDevice.RemoteNodeList["SequencerSetSave"].Execute();
// Start with the Set0
mDevice.RemoteNodeList["SequencerSetStart"].Value = (long)0;

// SEQUENCER CONFIG END
mDevice.RemoteNodeList["SequencerConfigurationMode"].Value = "Off";

// START CAMERA SEQUENCER
mDevice.RemoteNodeList["SequencerMode"].Value = "On";
mDataStream.StartAcquisition();
mDevice.RemoteNodeList["AcquisitionStart"].Execute();

// CAPTURE IMAGES

// STOP CAMERA SEQUENCER
mDevice.RemoteNodeList["AcquisitionStop"].Execute();
mDataStream.StopAcquisition();
mDevice.RemoteNodeList["SequencerMode"].Value = "Off";

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