trigger event every second?

hi there..
i'm writing rfid code now, and i got some problem with event.
i need to trigger the OpenCard() function automatically, so that whenever i placed my tag on the reader, it automatically triger the function and open the card.

To solve this problem, i'm thinking of calling the function 20 times every second. But i don't know what 'time' class/attribute to use to work with this.

Anybody can help me ?
Or may be another technique beside calling the function 20 times every second?

sorry for my bad english, and thx for reading anyway...

You can use the System Timer class, while shooting your process off in a separate thread that will run separate from the page's own thread.

As for calling it 20 times a second, it depends, why do you need it called 20 times a second?