Bernard:
Yes, it is necessary to restart after changing frequencies.
This is necessary to restart the engine timer. Also, if you tune the spindle
in 35 Khz and then switch to 25Khz, you have to retune. Any frequency
changes and all motors must be retuned. This is due to calculations
involving your actual timing periods to make everything as accurate as
possible.
The missing pulses you see are probably the bresenham divider in
operation. For exmple 25Khz is one pulse every 40us but 24.9Khz is still one
pulse every 40us one will be missing every 24999 pulses. This can look like
missing pulses.Most step/dir convertors to analogue simply charge caps so
there is no problem with this method, but you may be trying to use a circuit
type not so tolerant of this type of pulse timing. The steppers won't notice
it but your spindle VFD might.
Hope this helps,
Art
www.artofcnc.ca
