Data Acquisition Toolbox

The Samples to Acquire per Trigger

When a trigger executes, a predefined number of samples are acquired for each channel group member and logged to the engine or a disk file. You specify the number of samples to acquire per trigger with the SamplesPerTrigger property.

The default value of SamplesPerTrigger is calculated by the engine such that 1 second of data is collected, and is based on the default value of SampleRate. In general, to calculate the acquisition time for each trigger, you apply the formula

acquisition time (seconds) = samples per trigger / sampling rate (in Hz)

For example, to acquire 5 seconds of data per trigger for each channel contained by ai:

• set(ai,'SamplesPerTrigger',500000)
  

To continually acquire data, you set SamplesPerTrigger to inf.

• set(ai,'SamplesPerTrigger',inf)
  

A continuous acquisition stops only if you issue the stop function, or an error occurs.

Trigger Types

Acquiring Data