RE: servos

Yes, the Interfaces which are low in cost will place restrictions on performance, and <real time> goes first, and therefore the speed is limited. This improves with faster computers, but this scheme probably will not work on a system with a red hat sitting on top. Still the USB is available on most newer machines and might play a role of interest to some exploring their personal interests herein.

The funney part of the converging technologies, may be that as computers get faster and cheeper, the standard interfaces may begin to work in ways they were too slow for in the past. Metal will not get softer and easier to machine as time goes on.

As far as the printer interface goes, I'm thinking of the dual printer interface card option, giving you 16 bi-directional lines of data, plus an odd amount of handshaking and status lines between the two parallel ports available. If you look in your favorite cheep computer catalog, you find all sorts of standard I/O cards to drop in a slot. It seems to me that the fancy cards such as Servo to go give you a lot of bang for more bucks. If you can live
with less bang, then why not consider the concept that while you are even thinking about it, computer I/O in the standard formats will be 6% cheeper by the time you order it.

>
> Computer Interfacing cards and approximate price:
> ISA SCSI-II Controller card $50
> PCI USB I/O Card $40
> Dual port ISA Bi-directional Printer Card $35

[David Howland]

<In response to comment from Jon >

USB is a real exciting option, but I wonder, how long does it take for a request from a R/T module to be sent
through the USB driver to the custom motion box, and then for a reply to come back through the driver to the
R/T module. Actually, that can't work, anyway. So, if the R/T module had the code to manage the USB,
then nobody else could use it. Maybe with that restriction that the USB couldn't be used for any other purpose,
maybe this would work.

Same problem, then, with the SCSI interface, it would have to be a private resource to the R/T code.

And, the printer interface is just too narrow (8 data bits plus way too few control lines) to be a good
data path. Also, there are limits on how many printer ports you can have (unless you hack the address
decoder).

Jon

Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the discussion of shop built systems in the above catagories.
To Unsubscribe, read archives, change to or from digest.
Go to: http://www.onelist.com/isregistered.cgi
Log on, and you will go to Member Center, and you can make changes there.
For the FAQ, go to http://www.ktmarketing.com/faq.html
bill,
List Manager