Could you be more specific? The easiest way to communicate between programs would be using queues or unitialized shift registers in a subvi (LV2 style globals). These are two simple ways to share data between programs. Of course there are many ways to share data, these are some of the easier ways. For more help look in the LV examples or maybe post and example. Hope this helps.
BJD1613
Lead Test Tools Development Engineer
Philips Respironics
Certified LV Architect / Instructor