Hi, Let us break the problem into its building blocks..
1-Micro controller part 2- PC part 3- communication part
Micro controllers are now powerful enough to manage a large complicated machine on its own, so actually you can do all processing requirements there. So the need for host PC would be more of human interface, and a little complex arithmatic if needed, beter help support etc..
PC part, beleive it or not, an old 486 with windows 9x will have enough power to do the job, UNLESS we are talking about someting similer to audio or video recording where thousands or more samples per second has to be taken per second and storing it on hard disk as a contious streem.
Just don't run more applications that need much of processor attention, i.e. dedicated pc.
Communication link in PC serial mode can go up to 115200 b/s which translate to about more than 11 kbyte of data per second, and full duplex i.e 11k go and 11k back....
Long distance and noisy industrial environments, use RS485 instead of RS232 (a simple converter will do)
So VB is a breath to use and has a lot of features you may need to write pages of code to get it in any other language.
If you feel that a fuction or group of functions are too extensive and need faster language, write those in other faster language in dll form, like Delphi,power basic dll for windows or even C, still use the vb interface and call that dll as simple as you call vb own functions.
I use this way to replace an old Z80 computer running a fiber processing machine (preparation for weaving and dyeing)
Any more help I will be glad to..