"Bob Engelhardt" wrote in message
...
I'm using a dc motor & a servo amp to run the lead screw on my lathe. The
servo amp is an Advanced Motion Controls model 25A20:
http://www.a-m-c.com/download/datasheet/25a20i.pdf

I'm setting the speed with an analog input on pins 4 & 5 ("REF"). This is
described as "Differential Reference Input (±10 V Operating Range, ±15 V
Maximum Input)". My assumption was that this voltage could go to 15v, but
beyond 10v there would be no additional effect on the output. I was wrong.
The output continues to increase as REF increases to 15v. I didn't check
if it was linear in the 10 - 15v range.

The question is: is it a bad idea to use it in the 10-15v range? It might
be useful to have the extra output in certain special cases. E.g. rapid
reverse.

Thanks,
Bob

PS - is there another NG that might be better posted to?

+ & - 10V is a pretty common servo connection. You should be able to adjust
gain and perhaps signal pots to give you the full speed at 10V input if that
is what you desire. I'd recommend adjusting the drive to give you the
speeds you need (or maximum speed) with the 10V input, it may be easier on
the electronics and would be more likely to be compatible if you needed to
replace the drive some day. My CNC lathe has 240ipm rapids and this is done
with a +-10V input to the servo drives.

RogerN