On Sat, 1 Nov 2008, Frank Tkalcevic wrote:
> Date: Sat, 1 Nov 2008 10:32:45 +1100
> From: Frank Tkalcevic <[EMAIL PROTECTED]>
> Reply-To: "Enhanced Machine Controller (EMC)"
> <emc-users@lists.sourceforge.net>
> To: emc-users@lists.sourceforge.net
> Subject: [Emc-users] OT: wiring 5i20 + 7i33
>
> I'm about to start converting my lathe to cnc and I am wondering how other
> users of the 5i20 + 7i33 have wired it up.
>
> I have some +/-10v servo controllers that I am planning to drive with the
> 5i20+7i33 combo. My computer is about 3 meters away. I was planning to
> house the servos in an electrical enclosure next to the lathe, and
> obviously, the 5i20 in the PC. I was planning on putting the 7i33 in the
> electrical enclosure, and running the 5i20 signals from the PC to the 7i33
> in the enclosure. For cabling I was looking at SCSI 50 wire cables with
> centronics connectors on each end. I'll make up sockets on each end. I'll
> probably run 2 cables to get to another set of IO pins.
>
> Any thoughts on my plan?
> Should the 7i33 be close to the PC, or is it OK being far way? Should I run
> the analog/encoder signals through the long wire?
> Is a SCSI cable OK for this? I can't find any information about whether all
> wires are straight through. I vaguely remember seeing the words "twisted
> pair" in one of the description. Will 50 conductor ribbon cable be too
> susceptible to noise?
>
> Any comments would be appreciated.
>
> Thanks,
> Frank
>
> www.franksworkshop.com
It depends on how noisy your environment is and also the Revision on the 7I33
card. If you dont have a terribly noisy environmet, the current revision (E)
will work with up to 10 feet or so. Here the revision differences:
C revision - Weak encoder output drive in TTL mode not good for more than 2
feet at high speed
D revision - 24 mA drive buffers added to encoder signals
E revision - cable impedance matched parallel termination on PWM signals
for better analog linearity with long cables
Also if the flat cable is long, you may have to power the encoders from a
separate 5V power supply, due to drop in the 5V in the flat cable.
Peter Wallace
Mesa Electronics
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