Triggers

A trigger is an event that causes a sensor to acquire a single frame or image. You configure triggers on the Acquire > page, in the Trigger panel.

When a trigger is processed, the LED light pattern is strobed and the cameras expose to produce images. The resulting images are processed inside the sensor to yield a 3D point cloud. The data can then be used for measurement.

The sensor can be triggered by one of the sources described below.

If the sensor is connected to a Master 400 or higher, encoder and digital (external) input signals over the IO cordset are ignored. The sensor instead receives these signals from the Master; for encoder and digital input pinouts on Masters, see the section corresponding to your Master in Master Network Controllers.

If the sensor is connected to a Master 100 (or no Master is used), the sensor receives signals over the IO cordset. For information on connecting encoder and digital input signals to a sensor in these cases, see Encoder Input and Digital Input, respectively.

When using encoder triggering (available with line profilers), the current encoder resolution is displayed in the Encoder resolution drop-down as a reference when setting trigger spacing.

To set the encoder resolution, expand the Motion section and set the value in Encoder resolution.

Trigger source descriptions
Trigger Source Description
Time

Sensors have an internal clock that can be used to generate fixed-frequency triggers. The external input can be used to enable or disable the time triggers.

External Input

A digital input can provide triggers in response to external events (for example, a photocell). The external input triggers on the rising edge of the signal.

When triggers are received at a frequency higher than the maximum frame rate, some triggers may not be accepted. Use the Trigger Drops indicator in the Health panel on the Reports page to check for this condition; for more information, see Monitor - Measurement Stats, Health & Performance.

For information on the maximum input trigger rate, see Maximum Input Trigger Rate.

Software

A network command can be used to send a software trigger. For more information, Protocols (PLCs and other hardware).

Depending on the setup and measurement tools used, the CPU utilization may exceed 100%, which reduces the overall acquisition speed.

For examples of typical real-world scenarios, see Trigger Examples.

Trigger Settings

After you choose the trigger source, configure the other parameters in Acquire page > Trigger section.

Parameter Trigger Source Description

Source

n/a

The source for triggering the acquisition of frames (Time, External Input, or Software).

Trigger at maximum frame rate

Time

When this is enabled, frames are acquired at the maximum possible frame rate. The maximum frame rate is limited by the exposure, active area, and light duty cycle settings.

Frame Rate

Time

Controls the frame rate. Fractional values are supported. For example, 0.1 can be entered to run at 1 frame every 10 seconds.

Trigger Delay External Input

Specifies the amount of time or the distance the sensor waits before producing a frame after the external input is activated. This is used to compensate for the positional difference between the source of the external input trigger (for example, a photocell) and the sensor.