Re: Digest Number 433
Posted by
David A. Forsyth
on 2000-04-06 00:44:04 UTC
On 5 Apr 00 at 22:08, CAD_CAM_EDM_DRO@egroups.com scribbled
furtively:
a PIC based DRO with LED/LCD display, one per axis.
each one being capable of transmitting it's values down a serial
line, and having an incoming serial line too.......
so, if you just have one DRO, you can use it as is, or connect it to
a PC and have the PC do all those translation things, offsets etc.
if you have 2 or more DRO's, they cascade into one another. X feeds
Y feeds Z feeds the PC (or any order). each one just passes the info
along, but adds an ID number, so the PC can tell them apart.
operator setup tells the PC what ID number belongs to what axis.
now the PC can do all those nice things in relative space, feedrate
display, waypoints to file etc etc..... for ANY number of axis'
that the serial lines can reasonably transport the data. remember
that the last one in the chain is retransmitting quite bit of data
when you get to 5 axis. I used tob e able to calculate the bandwidth
required for this, but I'll leave it to better informed people for
now....
but it does keep the PIC program and data space simple, while
allowing fancier stuff to be done on the PC where space is not an
issue.
Living in South Africa
Flying power Kites
Chasing 3'6" gauge steam trains
http://www.ru.ac.za/departments/iwr/staff/daf/
furtively:
> Message: 1I think there's milage in doing it both ways in one box.
> Date: Wed, 05 Apr 2000 08:25:38 -0400
> From: Ron Ginger <ginger@...>
> Subject: Re: Digest Number 433
>
>
> > From: "james owens" <wotisname@...>
> >Subject: Re: PIC DRO
>
> >Do you require a DRO or just a counter? If it is the latter then spending good
> >money in doing the job for high accuracy is not the way to go. There are much
> >cheaper ways to achieve what you require. If it is the former then a line has to
> >be drawn because the PIC can only hold a limited amount of programming and it
> >would make sense to me to go for the higest resolution that is practical using
> >off the shelf parts that anyone can afford. I am not a programmer and this
> >question should really be answered by the guy that is doing the thinking bits.
>
> Im not quite sure what you mean here- the DRO sold by Shooting Star has
> a PIC micro inside it and it does everything needed for a DRO. I dont
> think a PC based DRO is very usefull- to much complication for a job
> that can clearly be done in just a small box and a PIC. But maybe thats
> because my shop is so small I could not get a PC monitor in by the mill.
a PIC based DRO with LED/LCD display, one per axis.
each one being capable of transmitting it's values down a serial
line, and having an incoming serial line too.......
so, if you just have one DRO, you can use it as is, or connect it to
a PC and have the PC do all those translation things, offsets etc.
if you have 2 or more DRO's, they cascade into one another. X feeds
Y feeds Z feeds the PC (or any order). each one just passes the info
along, but adds an ID number, so the PC can tell them apart.
operator setup tells the PC what ID number belongs to what axis.
now the PC can do all those nice things in relative space, feedrate
display, waypoints to file etc etc..... for ANY number of axis'
that the serial lines can reasonably transport the data. remember
that the last one in the chain is retransmitting quite bit of data
when you get to 5 axis. I used tob e able to calculate the bandwidth
required for this, but I'll leave it to better informed people for
now....
but it does keep the PIC program and data space simple, while
allowing fancier stuff to be done on the PC where space is not an
issue.
> Designing a DRO based on the US Digital linear encoders, with a simple--
> PIC in a box with an LED would be a very usefull project. I hate to
> compete with Shooting Star, because they are VERY nice people, but I
> have just never been moved by their rack and pinion scale.
Living in South Africa
Flying power Kites
Chasing 3'6" gauge steam trains
http://www.ru.ac.za/departments/iwr/staff/daf/