Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still there....

It sure sounds like noise.
I read the previous posts but I want to ask some
questions about the behavior:

With computer ON, encoder supply ON, and servo amps OFF (at supply)
does the encoder count still smoothly change when the motors
are turned by hand with all axes?

If so when the servo amp is turned on does the problem appear
with all axes? (of course it should have 0 input when turning it on)

Does the problem disappear if the servo amps are on but not enabled?

Is the behavior noticed with BOTH EMC and stgdiag programs?

Can you download the DOS version of stgdiag and run it from a temporary
DOS boot floppy? If so what are the results?

Is the 75174 IC enabled By +5 to pins 4 and 12 (if it is 16 pin dip
package)?

Now after the IC you should have 8 wires to each encoder. For me
there are 3 separate shielded twisted pairs for the encoder outputs
and +5 and a separate ground. The shields for the twisted pair are
hooked to star ground near the computer but LEFT UNHOOKED at
the encoder end 2 meters or so away.

Can you get a scope to measure the signals? Channels A+, B+, and I+
should be high and A-,B-, and I- low or vice versa relative to ground.

I still use a 1 meter ribbon cable in the control box to go from a breakout
board to the card. It is a special ribbon cable that uses twisted pairs.
What do you use?

What model of encoder are you using? What is the count per revolution?
How many rpm do you want to turn it?

What is the base address of your stg card? Have you tried changing it?

How are your other card dip switches set?

If you will please answer these questions it will help to diagnose the
problem.
We may need to look at the .ini file but if the behavior is also happening
with
stgdiag I don't think that is it.

Les

Leslie Watts
L M Watts Furniture
Tiger, Georgia USA
http://www.alltel.net/~leswatts/wattsfurniturewp.html
engineering page:
http://www.alltel.net/~leswatts/shop.html

----- Original Message -----
From: "Babar" <riet91@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>; <emc@...>
Sent: Friday, September 13, 2002 7:21 AM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Position counter stop updating....Still
there....


> Hi Forum
>
> We did many changes to our EMC system but still
> having the "Position Counter Stucking Problem"
>
> After reading various suggestion we did the following
> changes:
>
> 1. Converted the single ended encoder signals to
> diferential signals
> using 75174 ic. These modules are placed very near to
> Motor encoders.
> just about 2-3 inch away
>
> 2. We are now powering the encoders from an external
> +5V suply. We are
> already using 0.1 uf capacitors to dump noise at the
> output of the Power supply & the powersupply
> connections of 75174 modules.
>
> 3. In our system digital, Analog ground and earth
> connection are at the same point. We can not separate
> these AGND and DGND separate because of
> the internal construction of our servo drives and
> STG-II card.
>
> We ran the stg2diag utility program and still see
> unwanted/ strange big
> count values on each axis. this happens even when the
> slides are not moving however when we cut power to the
> machine and only keep PC ON then we dont see any such
> kind of unwanted / big values, the counters
> just keep stopped.
>
> Is it just a noise problem or is this may happen due
> to any wrong entry in the ini? should we post our ini?
>
> Please help us, else we too will be forced to say that
> "life without EMC..."
>
> Babar
> >
>
>
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