How to send a variable width TTL pulse using USB 6501

[Tracey.bat]

I am trying to send a TTL signal to a valve once a sensor has been triggered. The valve will need to open for different periods of time during different experiments to release a varying amount of liquid, is there a way of varying the TTL pulse width using a USB 6501 and LabVIEW 8.5?
 
Thanks  

[efreyre]

Perhaps &nbsp;you&nbsp; would want to make something a <a href="http://electronica.phpnet.us/foro/phpBB2/viewtopic.php?t=93" target="_blank">PWM, I have here a code that could be useful for you</a>.
this have been made on <a href="http://electronica.phpnet.us/foro/phpBB2/viewtopic.php?t=93" target="_blank">borland C++ builder</a>
&nbsp;
&nbsp;
&nbsp;
&nbsp;