Visio is controllable through ActiveX calls - as are Excel or Word. You should be able to use the same basic techiniques to communicate with Visio as you would use for the other two. It's all a matter of learning the proper control and methods to use. I would start with a search on MS' website for Visio and ActiveX.
Mike...
Certified Professional Instructor Certified LabVIEW Architect LabVIEW Champion
