Data Acquisition Toolbox

Example: Generating Timer Events

This example illustrates how to generate timer events for a DIO object. The callback function daqcallback displays the event type and device object name. Note that you must issue a stop command to stop the execution of the object.

You can run this example by typing daqdoc7_2 at the MATLAB command line.

1. Create a device object -- Create the digital I/O object dio for a National Instruments board. The installed adaptors and hardware IDs are found with daqhwinfo.

• dio = digitalio('nidaq',1);
  

2. Add lines -- Add eight input lines from port 0 (line-configurable).

• addline(dio,0:7,'in');
  

3. Configure property values -- Configure the timer event to call daqcallback every five seconds.

• set(dio,'TimerFcn',@daqcallback)
  set(dio,'TimerPeriod',5.0)
  

1. Start the digital I/O object. You must issue a stop command when you no longer want to generate timer events.

   • start(dio)
     

   The pause command ensures that two timer events are generated when you run daqdoc7_2 from the command line.

   • pause(11)
     

4. Clean up -- When you no longer need dio, you should remove it from memory and from the MATLAB workspace.

• delete(dio)
  clear dio
  

Starting and Stopping a Digital I/O Object

Evaluating the Digital I/O Object Status