My apologizes but it seems as i had a typo in the previous post. The way you need to call it is:
unitOpened.handle = ps3000_open_unit();
unitOpened2.handle = ps3000_open_unit();
You will also have to duplicate the unitOpened structure and name the structure as unitOpened2. You can also get around this by not using the unitOpened structure and simply name your handles handle and handle2 or something similar.
Crag Technologies, Inc