If I understand your question correctly then yes it is easily done. Simply turn Local Save on, Motion Detection off, and set the Save Interval to 30 seconds (or thereabouts - whatever value suits your needs).

Depending on what you want to accomplish, you would then either:

1) Turn Time Based Name on, which will save each frame to its own file. This is how you would probably approach making a time-lapse movie. Let a bunch of frame files accumulate and then run the Jpeg2Video utility to convert them to an AVI (or whatever - depends on which codec you select in Jpeg2Video)

2) Turn Time Based Name off, which uses a single file that gets overwritten by each captured frame. If you are making something like a webcam page with an image that only updates every 30 sec. then this would be a good way to go about it.