Re: [CAD_CAM_EDM_DRO] Re: Home switches.

In a message dated 7/9/2005 10:22:09 AM Eastern Daylight Time,
dave_mucha@... writes:
Are you asking to use the existing end or home switch in combination
with an encoder ?

As I understand, some encoders have a 3rd channel. a single point per
revolution.

It would appear that one could run the axis to the end switch and then
until that encoder point changed state.

That would represent the motor being in one exact location, and not
necessarly the screw or table. But, it does eleminate a chip or dirt
from influencing the home point.

Dave
You are correct, many encoders have a "Zero Channel" or "Zero Pulse" on in
them. Most of the ones I have used or worked with actually have two of them,
180 degrees apart on the round scale. You first make contact with a limit
switch (or you can use a proximity sensor) then the control begins to look for that
Zero Pulse, when it sees it, then the control knows it has reached the home
position. Pretty much all of your OEM machines use this type of system, it is
more accurate because, as you pointed out, it prevents metal or wood chips,
etc. from changing the actual position. However, the controller being used must
be designed to use that Zero Channel as the pusle is on a completely
different output.

I hope this helps some.

Randy A.


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