My Viper 200 Servo Drivers arrived the other day and I have had the chance to work with them over the past 2 evenings. I thought I would post some of my experiences and I encourage others to do the same.
These will be for a Milltronics Partner mill that I am restoring. I am using the original DC brushed servos, made by SEM, rated 4000RPM at 140Volts and 11 Amps. One motor had a bad encoder, so I have replaced all encoders with 300-line units from US Digital. I have worked with several stepper systems before, but this is my first experience with servos and I am learning as I go.
I started by making a power supply and the necessary cables. Larken included all of the mating connectors for the board to make it easier (although I do wish they had included enough jumpers for setting all parameters on the board- c'mon they are like a penny a piece!) Salvaging transformers, caps, and a rectifier from the Milltronics hulk I built a power supply that runs on 120V and outputs a clean 86Vdc. This should give me about 2500 RPM or 250IPM as the mill is currently geared- well more than enough speed.
The instructions are adequate, but not exceptional. I'd suggest a few changes:
+Adding to the "connections" photo explanations of all the lights
+Better details on configuring the pc terminal program (including a screenshot)
+A true step-by-step set of setup instructions (or even an online video!)
+Clearer instructions on how to wire encoders with only one wire per channel
My testing: I hooked everything up, testing the low voltage control stuff first. The pc interface using a serial terminal works well and provides nice clear information. The default values in the drive were set way too high, causing an oscillation (I=6). I hooked a function generator up along with some switches to provide manual step and direction for testing. Upon first startup the motor shook violently, and I reversed motor connections per the manual to correct the condition.
I fumbled blindly through my settings, not knowing what is "normal". I wound up with P=700, I=1, and D=1400. This gave a strong motor hold at stop, a crisp stop from 500RPM, and no unwanted oscillation or humming. I've looked at current/response curves on different websites, but was unable to get my oscilloscope to pick up a clean trace. I'd like a slightly more scientific way to test my settings other than "that looks about right". A test point that I could hook my scope to, like in the Gecko drives, would be nice.
All in all, a nice product so far. I'll post more as I get more experience.