Data Acquisition Toolbox

How Many Triggers Occurred?

You can find out how many triggers occurred with the TriggersExecuted property value. The trigger number for each trigger executed is also recorded by the EventLog property. A convenient way to access event log information is with the showdaqevents function.

For example, suppose you create the analog input object ai for a sound card and add one channel to it. ai is configured to acquire 40,000 samples with five triggers using the default sampling rate of 8000 Hz.

• ai = analoginput('winsound');
  ch = addchannel(ai,1);
  set(ai,'TriggerRepeat',4);
  start(ai)
  

TriggersExecuted returns the number of triggers executed.

• ai.TriggersExecuted
  ans =
        5
  

showdaqevents returns information for all the events that occurred while ai was executing.

• showdaqevents(ai)
     1 Start               ( 10:22:04, 0 )
     2 Trigger#1           ( 10:22:04, 0 )          Channel: N/A
     3 Trigger#2           ( 10:22:05, 8000 )       Channel: N/A
     4 Trigger#3           ( 10:22:06, 16000 )      Channel: N/A
     5 Trigger#4           ( 10:22:07, 24000 )      Channel: N/A
     6 Trigger#5           ( 10:22:08, 32000 )      Channel: N/A
     7 Stop                ( 10:22:09, 40000 )
  

For more information about recording and retrieving events, refer to Recording and Retrieving Event Information.

Repeating Triggers

When Did the Trigger Occur?