Would be nice to include an input pin on the shield ( maybe a terminal connection on rev’d shields ) for an emergency stop button. I might even expand on that idea with my system to have certain limit type switches around workspace, or overforce type switch on sled chain connections.
I know there is a picture of a power cutoff button mounted on a Maslow in the upper left corner.
You are much better off killing power to everything then asking software to perform some function. You don’t know if the emergency is caused by a failure in the software.