Re: EMC Running My Controller

In the emc doc it points out that the stepper pulses are written to the
parallel port at "an effective period of 200 microseonds for a full
up-and -down pulse or a 5 Khz frequency"
I did the math and they are right.
The reason that I was interested in the pulses per second was that I have a
servo system that reads the signals from the parallel port. It has a 200
count encoder on the motor . In quadrature it is 800 counts . 5000/800=6.25
RPS*60= 375 rpms
I may have to look at using the ISA buss.
-----Original Message-----
From: George Potter <gpotter@...>
To: CAD_CAM_EDM_DRO@onelist.com <CAD_CAM_EDM_DRO@onelist.com>
Date: Sunday, August 15, 1999 9:47 PM
Subject: Re: [CAD_CAM_EDM_DRO] EMC Running My Controller

>From: George Potter <gpotter@...>
>
>I don't know where the figure 5 Khz comes from, as the
>"normal" parallel port hardware (assuming based on that
>disclosed in the "original" IBM AT Handbook is only
>limited by how fast your software can write to it ....
>(up to the ISA I/O card bus speed). (I believe that
>even on "slow" machines it should be possible to get
>around 100 kbytes / second out the port. (The
>"newer" ECP (etc.) types of ports should support
>7 or 800 kbyte through put, if I remember correctly).
>(all of my support books are at work). The capacitors
>shouldn't be a limiting factor.
>
>If someone really needs to know, I can write a few lines
>of code, and see what I can get out of one (meaning
>hardware limits), but it will take a few days to get around
>to it.
>
>In a past life, I used the parallel port to run various production
>test hardware, and it was amazing what could be run that way.
>
>Regards,
>George Potter
>
>Jon Anderson wrote:
>
>> From: Jon Anderson <janders@...>
>>
>> Dan Mauch wrote:
>>
>> > Now that I have emc up and running I went back and read the
>> > docs. I discovered that using the parallel port you are
>> > limited to 5KHZ thru the parallel port.
>>
>> I don't know if this is true, or if it would help, but I was told that
>> there are small capacitors on the I/O lines of the parallel port.
>> Clipping these is -supposed- to greatly increase rate of data transfer.
>> Obviously, it would be better to try this on an add-in card than on the
>> motherboard...
>> I don't know enough about electronics to feel confident about what
>> capacitors to clip, nor measure the effects. Just thought I'd toss it
>> out for someone else to comment on.
>>
>> Jon
>>