Re: DAC to feed rate.

[Jon Elson <jmelson-at-artsci.wustl.edu>]

Tom Freedy wrote:

>
> Question,
>
>   How do you setup your DAC to the feed rate?
> IE: (Max speed of motors = 400 ipm) =  +10 volts.

The standard velocity command signals are historically
+/- 10 V.  So, you would decide the highest velocity the
system is capable of, and make +10 V cause the servo
amp to produce such a velocity.  Then, there are parameters
in the EMC .ini file that set the scale of the DAC, in volts.
There is some description of this in the document
 http://www.isd.mel.nist.gov/projects/emc/emcsoft.html

This computation is in mm/sec, I think.  So that 400 IPM
= 170 mm/sec, and you want 10 V output for that velocity,
I think you would specify :
OUTPUT_SCALE = 0.058 0
This is calculated as 10 V = 170 * scale or
    10 / 170  = scale

Jon