Re: Connection of hardware

[Ray Henry <rehenry-at-up.net>]

John 

>I forsee a bunch of coding I'll have to do to obtain the spindle speed.
>If I ask for 1300 rpm, it doesn't really have to be that exactly as long
>as I know what it is (e.g., 1304.67 rpm) to coordinate threading tasks.

I also want to use emc for lathe tasks and need the threading and high 
speed spindle coordinated with z.  Don't have a clue how to do it.

>I'm a long way from getting there yet. I'm not going to use xemc as is
>anyway since I want to personalize it (and I'm a X-Windows/Motif gui
>expert).

Sounds like you need to be a member of the EMC gui committee that Fred wrote
of today.

>There are opto-22 "quadrature" input modules that advertize to be used for
>encoders,
>but I know nothing about what I'm talking about, so I'm probably wrong :-(
>
>See http://www.opto22.com/datasheets/1053_SNAP_Quadrature.pdf
>
>They advertize that the max RPM allowed is 1,500,000 / encoder's pulses per
>revolution

I skimmed the .pdf listed and I don't think the output of these is compatable
with anything that I've seen around emc.  They put out a square wave pulse
each time the quadrature signal changes state. The pulse will be on one 
output if the rotation is forward and another if it's reverse.  The rack 
that this module goes into must implement an up down counter.  The max 
rpm with one degree resolution (360 ppr) would be about 4100 rpm.

I'm not convinced that you need opto isolation on the quadrature 
input to the stg board.  I'd use isolation on all the input signals.  And
use sockets so that I could replace smoked isolators.  
  
If the outputs went to an NPN transistor and pulled a relay near the stg, 
I don't think I'd bother there either -- just use the relay to isolate
power and load.

Jon E. had some breakout boards.  We really should work up a general
purpose stg interface board plan and get some made up for all the signals.

Ray