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DCx Cameras
4.2.3 Capturing Images
DCx Cameras support the capture of single frames (snap) and frame sequences (live) in trigger mode and
untriggered (freerun) mode. Select the image capture mode that best meets your application requirements.
Using events or messages , the uc480 driver can provide information to an application, e.g. about the
completion of image capture. You will need events and messages, for example, when you are using image
memory sequences.
4.2.3.1 Image Capture Modes
For more information on the capture modes of the DCx Cameras see also Camera basics: Freerun and
Camera basics: Trigger .
Freerun mode
In freerun mode, the camera sensor captures one image after another at the set frame rate. Exposure of the
current image and readout/transfer of the previous image data are performed simultaneously. This allows the
maximum camera frame rate to be achieved. The frame rate and the exposure time can be set separately. The
captured images can be transferred one by one or continuously to the PC.
If trigger mode is active, you need to disable it with is_SetExternalTrigger() before activating freerun
mode.
Single frame mode (snap mode)
When is_FreezeVideo() is called, the next image exposed by the sensor is transferred. You cannot use
the DCxCamera flash outputs in this mode.
Continuous mode (live mode)
When is_CaptureVideo() is called, images are captured and transferred continuously. You can use the
DCxCamera flash outputs.
Trigger mode
In trigger mode, the sensor is on standby and starts exposing on receipt of a trigger signal. A trigger event can be
initiated by a software command (software trigger) or by an electrical signal via the camera’s digital input (hardware
trigger). For the specifications of the electrical trigger signals, see the Specifications: Electrical specifications
chapter.
The trigger mode is selected using is_SetExternalTrigger() .
Software trigger mode
When this mode is enabled, calling is_FreezeVideo() immediately triggers the capture of an image and
then transfers the image to the PC. If is_CaptureVideo() is called, the triggering of image capture and the
transfer of images are performed continuously.
Hardware trigger mode
When this mode is enabled, calling is_FreezeVideo( ) makes the camera ready for triggering just once.
When the camera receives an electrical trigger signal, one image is captured and transferred.
If you call is_CaptureVideo() , the camera is made ready for triggering continuously. An image is captured
and transferred each time an electrical trigger signal is received; the camera is then ready for triggering again
(recommended procedure).
Freerun synchronization
In this mode, cameras running in freerun mode (live mode, see above) can be synchronized with an external
trigger signal. The cameras still remain in freerun mode. The trigger signal stops and restarts the current image
capture process. You can use this mode to synchronize multiple cameras that you are operating in the fast live
mode. Not all camera models support this mode (see is_SetExternalTrigger() ).
Notes
The freerun synchronization mode is currently not supported by DCx Cameras.
In trigger mode, the maximum frame rate is lower than in freerun mode because the sensors expose and
transfer sequentially. The possible frame rate in trigger mode depends on the exposure time.
Example: At the maximum exposure time, the frame rate is about half as high as in freerun mode; at the
minimum exposure time, the frame rate is about the same.
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