To be pragmatic what he is really after is a result rather than the learning experience.
Thanks for your interest in my problem.
I am making a machine that measures a camshaft.
I need to measure the cam to get information about the design of the current cam is so that I can compare the original design to the new design.
The machine uses two input devices; a rotary encoder and a linear gauge.
The idea is that I will rotate the cam (attached to the rotary encoder) and then for each position of rotation I send the value through the serial port to a VB program that I wrote.
This much I have working.
The next challenge is triggering the linear gauge to measure the position of the cam follower each time the rotary encoder changes value.
I would really prefer to do this with the Arduino if possible but it looks like code for reading this kind of device is very specialized and complex.
There are devices called smart cables that might do what I need, I will find out today, they are about $200 I think.