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

[John Sheahan <jrsheahan-at-optushome.com.au>]

Can I ask a couple of related questions 

Do you ever disable the 26LS31?  (which is what I know the 
 SN75174 as in this part of the world)
 Better not to here.

Is the pair terminated (ie ~100 ohms across it) at the load end
  well worth doing! 
  (the pair is the two wires connecting the the A and /A output pins
   through to the far end)

Is the pair run as a twisted pair?
  helps, but depends on your wiring.

Do you use a 26LS32 or similar to receive the differential signal?
  essential

if a diff pair is used properly - it is a LOT more noise free than a
single ended system.

do you have any test equpiment (eg oscilloscope) to measure 
noise levels?

regards, john





On Fri, Sep 13, 2002 at 07:30:44AM -0400, Babar wrote:
> 
> 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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