Re: Low cost Servo Controller

Steve Carlisle wrote:

> From: "Steve Carlisle" <quatsein@...>
>
> Jon, the PWM amps from Advanced Motion Controls accept
> a digital signal. How would the STG card control that servo
> drive.

The STG card expects the servo amp to accept analog input.
These AMC amps apparently expect the PWM waveform to
be generated by the CNC control. They are totally incompatible
with EMC anyway, as the PWM waveform controls motor current,
but the EMC is sending a velocity command to the servo amp.
So, the servo amp must take velocity in, compare to the tach
signal, and compute internally what motor current is desired.
(This is an easy computation, at least at the first order, well
within the capability of an op-amp.)

> The Analog amps they sell condition the -/+ 10V signal
> into a PWM signal to drive the bridge. Do the amps you designed
> operate on this principal.

Yes, this is similar to my amps, assuming they use tach to sense
velocity.

Jon