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IDS peak 2.14.0 / uEye+ firmware 3.42

Navigation: B: Operation of uEye+ cameras > Operating a camera > Using digital inputs/outputs

Synchronizing cameras using digital I/Os (master-slave)

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When your system consists of multiple cameras, you might want to make them capture the images at the same time or in a defined time sequence.

1.If your requirements in terms or timing are not very high, you can use the software trigger mode and send the TriggerSoftware command to all cameras one by one. There will be a non-deterministic delay for each camera due to the different transmission times, but for some applications the timing is accurate enough.

2.Connect the same hardware trigger signal to all cameras.

3.Use one camera as master and trigger all other cameras with its output signal. Compared to hardware trigger, this solution needs no additional trigger source. Compared to software trigger, this solution has a deterministic trigger delay and all cameras start the exposure at the same time.

hint_info

Note that the flash signal will not match precisely at very short exposure times, as almost all sensors have a jitter in the delay.
Fig. 92: Master-slave camera setup

Fig. 92: Master-slave camera setup

hint_info

Note on I/O pinning and circuits

For I/O pin assignment and circuit information for your camera model, refer to the technical manual of the respective camera family.

You might need additional hardware for your synchronization signal if:

•Using USB3 cameras

•Connecting many slave cameras to one master camera

•Using long cables

hint_notice

NOTICE! You should not mix opto-coupled and non-opto-coupled lines (LineFormat = LVTTL or TriState) without signal processing hardware (level and direction). This could damage your camera.

Configuration

Each camera, master and slave, is configured to start the image capture on a signal on the physical line, as explained in hardware trigger mode.

Camera

Line

Description

Master

Line 0

Hardware trigger signal input

Line 2

Connected to Line 2 of slave camera

Slave

Line 2

Connected to Line 2 of master camera

Master camera configuration

The master camera uses a timer to generate the signal for the physical line. The duration of the timer corresponds to the duration of the signal on that line.

// Timer duration defines the signal duration for the slave cameras (us)
TimerSelector = Timer0;
TimerDuration = 1000.0; // 1ms
TimerTriggerSource = ExposureTrigger;

The source for the output line is this "Timer0Active" signal (or "Timer1Active", if you use "Timer1"). Using inverted GPIOs instead of opto-coupled inputs and outputs keeps delays as small as possible.

// Configure the output line, preferrably a GPIO
LineSelector = Line2;
LineMode = Output;
LineSource = Timer0Active;
LineInverter = True;

Now the "ExposureStart" trigger can use exactly the same signal on the output line, that is also sent to the slave cameras to synchronize capture times.

// Configure ExposureStart Trigger
TriggerSelector = ExposureStart;
TriggerMode = On;
TriggerSource = Line0;

Now, the master camera's image acquisition can be started.

// Start Acquisition
AcquisitionStart();

Slave camera configuration

The slave cameras receive the synchronization signal on one of the input lines. Using GPIOs instead of opto-coupled in- and outputs keeps delays as small as possible.

// Configure the input line, preferrably a GPIO
LineSelector = Line2;
LineMode = Input;

Use the synchronization signal for triggering "ExposureStart".

// Configure ExposureStart Trigger
TriggerSelector = ExposureStart;
TriggerMode = On;
TriggerSource = Line2;

Now, the image acquisition on the slave cameras can be started.

// Start Acquisition
AcquisitionStart();

Fig. 93: Basic timing diagram for master slave mode

Fig. 93: Basic timing diagram for master slave mode

Trigger delay for timing corrections

You can use the TriggerDelay parameters to fine-tune the camera timing. Add the configuration to the parameters above.

Master Camera Configuration: Add the TriggerDelay to adjust possible delays due to signal transfer on the lines and through the digital I/Os.

// Configure ExposureStart Trigger
// ...
TriggerDelay = 30.0;

Slave camera configuration: Add the TriggerDelay to adjust slight timing differences between slave cameras, if necessary.

// Configure ExposureStart Trigger
// ...
TriggerDelay = 5.0;

Fig. 94: Timing diagram for master slave mode with timing adaptions using trigger delays

Fig. 94: Timing diagram for master slave mode with timing adaptions using trigger delays

Hardware signal as master trigger

You can use a signal on an input line as master trigger signal instead of the software command.

Master camera configuration: Add the TriggerDelay to adjust possible delays due to signal transfer on the lines and through the digital I/Os.

// Configure ExposureStart Trigger
TriggerSelector = ExposureStart;
TriggerMode = On;
TriggerSource = Line3;
TriggerActivation = FallingEdge;
TriggerDelay = 30.0;

Then the timer configuration changes, too.

// Timer duration defines the signal duration for the slave cameras (us)
TimerSelector = Timer0;
TimerDuration = 1000.0;
TimerTriggerSource = Line3;
TimerTriggerActivation = FallingEdge;

Slave camera configuration: The configuration for slave cameras is the same. Add the TriggerDelay to adjust slight timing differences between slave cameras, if necessary.

// Configure ExposureStart Trigger
// ...
TriggerDelay = 5.0;

Fig. 95: Timing diagram for master slave mode triggered by a hardware signal

Fig. 95: Timing diagram for master slave mode triggered by a hardware signal

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