Hi,
not quite sure yet but yes it would appear that you can program the resolution of the encoder...page 1.4
The number of steps per rotor revolution is adjustable between 16 and
65536.
If that the case then why choose max resolution of 65536? That equates to and angular resolution of 20 arc seconds! If your machine is rigid
and accurate enuf to demand a resolution of 20 arc minute let alone 20 arc second then you should be on a professional forum not a hobbyists one!
Additionally if you think you are going to successfully signal your drive at close to 4MHz your dreaming.
The solution I came up with for my servo driven spindle is:
Program the drive to operate in two different modes, the first, simple velocity mode using analogue voltage and, the second, with step/dir position
control.
Most of my milling ops can be done under plain velocity control, in fact its quite adequate to have just a knob you lean over and twist until the tool is
cutting as you want and the leave it there for the rest of the op...in some cases hours. This is the first of the control stratgegies and is selected by one
digital input (pin4 from memory) being held low by Mach. When I want position control for rigid tapping I go to the other mode by asserting the input
pin high. Typically when I'm tapping I don't tap at 3500 rpm! 100 rpm is fine and consequently the pulse output rate is 13kHz, in fact well within the
pulse rate of a parallel port let alone my ESS. As it turns out ESS can signal 467kHz no probs and my drive can receive 500kHz with differential signalling
but transmitting signals of that frequency can be fun and ultimately not even really useful or required for mill operations.
I haven't read the Bosch manual enuf to know whether it allows this dual mode strategy, my Allen Bradley drive does and I've seen it offered in other
makes as well and guess it is therefore standard fare for modern drives. If it is it would allow you to get simple speed control running and then put
your thinking cap on for the indexing mode. I doubt you will need anything like the max speed of the spindle when indexing and so when you 'gear it
down' (electronically speaking) you don't have to sacrifice resolution hugely and yet still end up with a pulse rate that means you don't have to be an
RF/ High Speed Digital engineer to get it to work.
Craig