I understand, but my point is this, Excel has computational ability that Visio doesn't. They both have object models and utilize VBA. The advantage that Excel brings is multi-fold: computational ability, much better VBA documentation for developing custom solutions, and many 3rd party apps. The advantage that Visio brings is its core drawing features. It just seems that if you're going to put a lot of time into developing a solution, utilize the software that has the most power, or combine the two.
I would encourage you to investigate developing macros within Excel. Thru them, you can get the interaction you need. Case in point, I developed a PLL analysis program using Excel/macros. It allowed you to specify gain, loop BW, phase margin, and circuit topology. Then, generated the component values, and plotted the responses: open loop, closed loop, step response, jitter. In addition, it allowed definition of the reference source characteristics. Looking at the plots, you could see where the major phase noise contributors were, make component changes, or loop definition changes, and obtain an optimum response. That's pretty interactive. The point is that Excel has huge amount of analysis power that Visio lacks, you just have to tap into it.
That's all rhetorical, just trying to provide a different perspective.
Bottom line, Visio great for documentation, allows embedding of other apps. Excel has great computational ability, better fundamental charting capability. Both utilize VBA and allow powerful, custom solutions. Either way, if you can't leverage existing work, you'll need to do significant custom development.
HTH
Wapperdude
