[Al Skierkiewicz]

Dan,
In looking through the on line manual for the 6009 it is possible to condition the signal externally with clamp diodes and noise circuitry to give a good signal at the input of the 6009. I have to agree that measuring the output of the Victor feeding a motor will expose the measuring device to voltages in excess of 100 volts with extremely fast rise times particularly during direction reversals. Simple passive techniques can put these signals under control. If you are interested in data acquisition on these excursions, a simple balanced "H" pad would give the scale you need to accurately convert the high voltage pulses to something the ADQ can handle. (at the sacrifice of low voltage resolution)
However, there is not much information to be gleaned from a simple voltage monitor on the output of the speed controller. Monitoring the input current to the controller tells so much more about the motor behavior and loads. For instance, monitoring the input current on a dual Chalupa feeding a transmission will tell if there is a shared load on both motors, a mechanical problem with coupling on one motor compared to the other, the failure of one motor/controller set, changes over time in the system and accurate comparison between drives on both sides of the robot.