The basic question is: have you any daq card (and which one) or you want to create a software timer?
In the first case I suggest you to look into the resource library, that is full of examples in the timer/couter cathegory. You could start for example from this page:
http://zone.ni.com/devzone/devzoneweb.nsf/opendoc?openagent&ACB0FBF3A736BCA78625686D00582E6B&cat=C7029C9ACBD3DF7386256786000F8EE6
to look at a clock obtained with a DAQ-STC equipped card (all e-series devices), and use it as a basis for your countdown timer.
Another way, but I haven't found any example for it, should be to use Down Counter or Divider Config.vi to generate a 1 Hz timebasis and use it in a down counter with the desired initial count, and decide what to do when it reaches TC.
If yo
u are looking at a software timer you could use some of the vis in the time & dialog palette
If you add some details more about your situation we can help you more.
Roberto
