Re: [CAD_CAM_EDM_DRO] Re: serial vs parallel port

On Wed Nov 5 09:16:08 2003 Jon Elson wrote:

>ccq@... wrote:
>
>>On Tue Nov 4 22:22:06 2003 Don Rogers wrote:
>>
>>>>Dear group can EMC use the RS232 port (serial) instead of the printer
>>>>port?
>>>>
>>>>
>>You're forgetting that there's a lot of old, now cheap, terminal server cards,
>>SCSI terminal servers and what not out there. I have one of the later, and it
>>seems to me that 8 serial and one parallel port could do a lot, especially at
>>115200 KBaud. That's also plenty to have some sync signals left over. Of
>>course, the hard/software hand shaking signals could be made to do a lot, too.
>>figure an axis per port, and go from there. One could be running a mill and a
>>lathe simultneously, and have room left over for a lot of things.
>>
>>
>These termial servers have NO guarantee of timing whatsoever! You can't
>even begin to think about controlling a real-time process with such devices.
>There could be tenths of a second gaps in the data flow the way these units
>work.
>
>Jon

I'm sure the oldest stuff has such issues to contend with, IRQs and so forth,
but most of the newer stuff handles it pretty well. The SCSI unit I have can
handle all 8 ports at 115200 simultaneously. That's not counting the parallel
port, but It might be included there, too, can't say for sure. In any case,
that's plenty fast enough for the job, with lots of room left over for global
synching, and more. There are also networking versions, too.

Bill


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