Karl Townsend wrote:

Can i ask how its wired in EMC? The limits switches on my control use
24 volt DC and are wired NC to an opto isolator. This is a very noise
resistant design. I'm curious if you can do the same in EMC.

You can do ANYTHING in EMC. But, Igor is using my (Pico Systems) PPMC board
set. It has an isolated 5 V power supply (DC-DC converter) on the
digital I/O board,
and 16 general-purpose opto-isolated inputs. There is a default
assignment of these,
with a + limit, -limit and home switch assigned for each axis. So, a
3-axis machine
uses up 9 digital inputs. EMC2 provides different messages for each
limit tripped condition
(Machine is on + X limit switch). The default config file set will
inhibit motion past a limit
switch (except when homing and the HOME_IGNORE_LIMITS parameter is set
for that axis).

Of course, you can wire up any different gear you want, and connect it
to EMC's functions
however you choose, in either HAL or ClassicLadder.

All my servo amps have L-C output filters, so I just don't have this
sort of trouble with them.

Normally closed contacts are the best way to do things, as you say. The
way I have the
DIO board set up, and electronic sensor with NPN output can also be
used, but the DC-DC
converter doesn't have enough extra capacity to power the sensor itself,
just to sense the
output.

Jon