estop sense

[dlantz-at-armorholdings.com]

I'm betting that this topic has been covered, and I'm just not doing a good
search job here.  Anyhow, I'm wondering if anyone here knows how to
change/add the estop sense to minimillio?  (more newbie questions to follow)
has anyone written an EMCIO module (is that what bridgeportio and minimillio
are called?) for a three axis with an 'on' and estop sense... like for a
waterjet cutter? (thanks in advance)
---Dave L.