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« on: February 03, 2011, 06:49:25 PM »
I probably have more experience with servos than steppers. I would say the main reasons I went with servos is Constant Torque, Velocity, Acceleration and Closed Loop to motors.
I am not an expert on exactly how Mach does things but as Mach is a controller working under windows it is a buffered system. Jogging does not have a planned path, Mach just sends out pulses and when the key is released Mach slows the pulses at the acceleration in motor tuning. Mach obviously keeps track of the pulses it sends out so can update the position. With feedhold however the toolpath has already been planned and buffered so when you press feedhold you are interrupting the planned toolpath so I would think Mach has to interrupt whats in the buffer, recalculate and refill the buffer.
As said I am no expert but that is just my interpretation of what is happening.
I still think the DSPMC is slowing things down but as said before Feedhold will not be as fast as stopping a jog, so if the feedhold is too slow then likely you will have to either try EMC or go with Milltronics or similar.
Hood