Electronics and Software
Engineering Innovation

Analog Trigger Accuracy

The analog trigger circuitry compares the voltage of the trigger source to the output of programmable trigger DACs. When you configure the level (or the high and low limits in window trigger mode), the device adjusts the output of the trigger DACs. Refer to the specifications document for your device to find the accuracy and resolution of the analog trigger DACs.

To improve accuracy you can:

  • Use an AI channel (with a small input range) instead of PFI 0/AI START TRIG as your trigger source. The DAQ device does not amplify the PFI 0/AI START TRIG signal. When using an AI channel, the PGIA amplifies the AI channel signal before driving the analog trigger circuitry. If you configure the AI channel to have a small input range, you can trigger on very small voltage changes in the input signal.
  • Software-calibrate the analog trigger circuitry. No hardware calibration is provided for the analog trigger circuitry. In addition, the propagation delay from when a valid trigger condition is met to when the analog trigger circuitry emits the Analog Comparison Event may have an impact on your measurements if the trigger signal has a high slew rate. If you find these conditions have a noticeable impact on your measurements, you can perform software calibration on the analog trigger circuitry by configuring your task as normal and applying a known signal for your analog trigger. Comparing the observed results against the expected results, you can calculate the necessary offsets to apply in software to fine-tune the desired triggering behavior.