Re: [CAD_CAM_EDM_DRO] Re: serial vs parallel port

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?
>
>This bring us a question I have had for a few months now. How can you
>truly synchronize multiple axis when driving them individually via a serial
>interface, IE from an indexer card vs a step/direction approach from a
>parallel port. The serial approach indicates giving one axis it
>instructions and the going to the next axis and giving it it's instructions.
>
>It seems to me that the indexer approach of sending serial commands to a
>single axis, however fast that can happen would lead to a bunch of
>individual movements not necessarily related to the goal at hand..
>
>Having looked at this for a while, I ended up stripping the indexer cards
>from my drivers to go to a step direction from a single port approach in
>the hopes that a single Command structure would be better than a
>discriminate command structure..
>
>Any discussion on this???
>
>Don

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.

Bill

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