Re: [CAD_CAM_EDM_DRO] Encoder Signals

For long runs I use cable that consists of 3 shielded twisted pair
in a differential configuration- A, Anot, B, Bnot, I, Inot. Power
(+5v and return) is wired elsewhere. The shields are hooked up
at one end only.

I find this works well even when the cables are laying right next
to PWM motor power leads running 20 amps. They end up all
being bundled in flexible Igus energy chain conduit.

Don't have differential output encoders? A couple dollars worth
of parts can convert them.

In the past I have had problems with single ended (TTL) encoder
lines and noise so I strongly suggest the differential approach.

As a last note make sure cables are rated to handle the thousands
of cycles of flexing that they will get! CAT5 cable is solid conductor
I think, so might it not be too good for this.

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
Surplus cnc for sale:
http://www.alltel.net/~leswatts/forsale.html

----- Original Message -----
From: <empireweld@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Sunday, January 05, 2003 11:31 PM
Subject: [CAD_CAM_EDM_DRO] Encoder Signals


> I am building a large gantry flame/plasma cutter.
>
> I'll be using servos with Gecko 320's.
>
> My longest run will be about 18' from controller.
>
> What type of wire should I use for encoder signals?
>
> Shields on 5V and ground or just A and B?
>
> RG45 or Cat 5 twisted pair A with B and 5V with ground?
>
> Should I use ferite beads on encoder or power leads?
>
> The servos I have are low inertia types and power leads
> are twisted tightly.
>
> Does this twisting minimize EMI or is it just pretty?
>
>
> Any help would be appreciated
>
> Thanks
>
> Doug
>
>
>
>
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