I just received one of those inexpensive laser tachometers and used it to check the actual NM200 spindle speed vs. the Mach3 command. The speeds are off a good bit, as I knew going in. At this time, a mach3 speed of 500 reads over 1200 on the tach, and each increase of 100 RPM in mach3 increases the spindle speed by 270 rpm. The VFD display shows numbers close to the tach, and I have been adjusting the mach3 speed in the past so that the VFD shows the speed I want.
Does anyone with a series 1 NM200 have correct speeds via mach3, and if so will you share your XML, or a screenshot of the spindle motor setup screen.