Re: digital servo controller to offload the Parallel Port?

[Dave Engvall <dengvall-at-charter.net>]

John, et al
There are lower cost solutions if one wants to work at it. Think about using
Dan Mauch's card for the encoders and an acrosser D/A. Only 12 bits, 3
channels and a little slow at maybe 1 KHz but worth a try for the price. The
code for the D/A is only a few lines but I didn't know enough to link it to
emc. The code for the encoders already exists.  After you beat the software
over the head you will still need to built some amps to offset the unipolar
output to +/- 10 v. A current to voltage converter should be easy. I think
you might get the whole thing....to the voltage output for $250. Then you
can worry about servo amps and motors (plus encoders) and some safety
(limit) switches and you are at least close.

I think Eric was working on a low cost solution also but don't know how far
along he is. 

Dave Engvall


On 12/19/02 8:43 AM, "j.guenther" <vze2z45u-at-verizon.net> wrote:

> 
> What Les said is true but it would be really nice to have a lower cost
> solution to servo control with EMC than the STG card.  Before you all flame
> me, I know that you can use Gecko 320 / 340 drivers and the there is PPMC
> from Jon Elson and maybe some other solutions.  IMHO for home shop use the
> STG cards are really cost prohibitive, at least in my shop.
> 
> John Guenther
> 'Ye Olde Pen Maker'
> Sterling, Virginia
> 
>> -----Original Message-----
>> From: emc-at-nist.gov [emc-at-nist.gov]On Behalf Of John Griessen
>> Sent: Thursday, December 19, 2002 10:39 AM
>> To: Multiple recipients of list
>> Subject: Re: digital servo controller to offload the Parallel Port?
>> 
>> 
>> 
>> Les,
>> 
>> I understand that emc uses the low cost of the mass produced PC to great
>> effect.   It just seemed Till knew where a performance limit was when
>> using the parallel port, and I was asking.  I have not played with an
>> emc driven machine yet.  Is there anyone in  Austin TX using one?
>> 
>> John Griessen
>> On Wed, 2002-12-18 at 16:30, Les Watts wrote:
>>> 
>>> Hi, John
>>> 
>>> The whole idea with EMC is really host signal processing.... the
>>> computer cpu does all the servo loop calcs in a real time
>>> operating system. Even a very slow old commodity computer has
>>> enough processing power to do a high performance job. So it does
>>> not need outboard processors.
>> 
>> 
>>> Les
>>> Leslie Watts
>>> L M Watts Furniture
>> 
>> 
>> 
>> 
> 
>