Digital Inputs / Outputs; Using Digital Inputs/Outputs; Flash Timing (Trigger Mode) - THORLABS DCU223x Operation Manual And Sdk

2.8 Digital Inputs / Outputs

All DCx cameras (see Model comparison
outputs that can be used for triggering the camera and for flash control. DC3240x cameras have in addition general
purpose I/Os (GPIO). Use of the GPIOs for flash control is possible to a certain degree. External triggering via the
GPIO is not supported.
See also:
Basics: Trigger mode
uc480 Viewer: Input/output
Specification: Electrical specifications
Programming:
is_IO()
280

2.8.1 Using Digital Inputs/Outputs

Digital input (trigger)
Models with optocoupler input can use the digital input for externally triggering the image capture, or query the
applied signal level.
In trigger mode , a digital signal is applied to the camera's input. You can determine whether the camera will
19
respond to the rising or falling edge of the digital signal. After an internal delay, the sensor is exposed for the
defined exposure time. The captured image is then transferred to the PC.
On models with general purpose I/Os (GPIO), you can query a voltage level at these inputs (TTL compatible).
Digital output (flash)
The digital outputs can be used in both freerun mode and trigger mode. You can synchronize the output level to the
exposure time or set it statically.
Models with optocoupler output allow control of a DC voltage applied to the output. This allows controlling a flash,
either directly or via a separate flash controller unit. Models with general purpose I/Os (GPIO) can output a voltage
at these outputs (TTL compatible).
Note
Please read the notes on I/O wiring for your camera model in the
Note
The settings specified for the digital output will be reset when the camera is disconnected from the PC or the PC is
powered down.

2.8.2 Flash Timing (Trigger Mode)

When using the digital output for flash control, you can set the delay and the duration of the flash. The flash timing
can be adjusted manually or automatically by the camera driver.
Note
Sensor latency and delay times The sensor latency is due to a number of technical factors, including sensor type,
image geometry, pixels clock and, with CCD sensors, the exposure time. The latency is constant for a specific
combination of parameters.
Trigger delay , flash delay and flash duration
352
The following illustrations show a schematic view of the image capture sequence. The sensor exposure and
readout times and the transmission times depend on the camera model and the current parameter settings.
Automatic flash
If flash delay = 0 and flash duration = 0, the flash signal is automatically synchronized to the exposure time. The
automatic flash feature has the advantage that the flash is synchronized automatically if the settings for image
geometry or camera timing are changed. The disadvantage is that the flash signal is active slightly longer than the
exposure time. The flash duration with automatic flash is longer for rolling shutter sensors than for global shutter
sensors.
© 2013 Thorlabs GmbH
), except DCC1545M and DCC1645C, come with opto-isolated inputs/
459
19
104
487
429
Electrical specifications
are optional and can be set by software.
2 Camera Basics
chapter.
487
47