I have their Apollo III system.  I don't know which Hicon that is.  Problem is that I set my VFD to give me 15-137 Hz.  OK took spindle tach readings when radn spindle straight from VFD.  recorded those #'s.  Then went into Mach and commanded ridiculously low RPM's with slider all the way down and ridiculously fast rpms with slider all the way up.  RPM's were not the same as when run off the VFD.  Low end rpms were higher and high end rpms were lower, so I was scratching my head.  Then hooked up DMM to 0-10V output and Gnd.  I checked and at slowest RPM get 1.259 VDC and at fastest rpm commanded get 9.83 VDC.  Even if there was a Pot to adjust, WTH?   I guess I would bring it all down by 1.259 VDC so high output would be 8.571 which is ridiculously off and at least low output would be correct.  I also got 21 Milivolts when nothing was commanded.   Suggestions?  Anything I should check for?  Everything else seems fine. Adjusting up my VFD freq is going to be my last option.  I would like to get the PWM output fixed proper, if possible before monkeying around with my min and Max Hz setting on the VFD. Thought I would see what the Vital systems guys have to say before I can get together with the Machmotion folks who are alway helpful.     

its a 7752 and some kind of proprietary machmotion BOB its plugs into.