If you remember your Freshman Calculus (boy, am I dating myself -- I should have said "High School Calculus"), you will recall that Speed (really, velocity) is the derivative of position, approximated by "Change in position per (small) Change in Time". LabVIEW is one of the few Programming Languages that has Time as a "real" part of the language (see the Timing Palette on the Block Diagram). It has a While Loop inside of which you could put a "Wait" function to "clock" the Loop, it even has a "Timed Loop" (which is better used in Real-Time OS environments, rather than in Windows). So if you want to move at a speed of, say, K units/sec (e.g. K meters/sec, or K °/sec for a rotation), you could set your Loop clock to, say, 10 ms and each time through the loop add K * 0.01 sec units to your current position. Because Position is changing each step through the Loop, you want to keep it in a Shift Register, so on entering the Loop, you wire in Initial Position (to initialize the Shift Register), then inside the Loop, you use the current value, update it by K * dt (where dt is your Time interval, such as 0.01 sec), and store it in the Shift Register for the next time through the Loop.
If you are still having problems, attach your VI (or VIs) (no pictures, please) and someone will probably help.
Bob Schor
