No electrical code that I know of permits a software-only emergency stop because they often only disconnect control power and can leave the motor/pump/heater running. There are too many things that can go wrong - the controlling computer gets busy or hung, response time is too long, the operator has trouble finding the right key and program button, etc. The only E-stop that the NEC, OSHA, or UL allow is a readily accessible hardwired button that removes not only control power but also operation power.
E_Stop pigtails are cheap. Why take a chance.
1 Like
Related to your question of using the buttons on the control box: yes I do and they work well, for example to quickly vacuum an area by hand or to double check something i pause the job and restart it using the play button… only thing I’m unhappy about is that when one needs to act really fast (!) it can take a few split seconds to decide which button to press as they look the same, so one of my planned add-ons project is to 3D print (or cnc mill) some bigger and visually striking button « covers » to add on top of the current 3 button stubs, so as to increase affordance of each button and make it even faster to pause or stop a job. This being said and in the perfect longmill world I could see the use for a big red button that would both pause the job and cut the mill power, that would be the ultimate great thing to have, but unfortunately beyond my electronic skills 
2 Likes