Is software Estop allowed

Software Estop in the form of UI/HMI touchscreen, flat panel display driven by mouse/keyboard, software commands (G code …) and membrane switches are NOT ALLOWED.

Control regulation rules (common sense) calls for external hardwired red mushroom push button.
Emergency stop push button must be designed to fulfill the following requirements:

• Mushroom-head shape to make it easy to push
• Coloured red and mounted on a bright yellow background
• Push button must remain in latched position after it has been pushed
• Resetting of the Estop by pulling or twisting alone shall not resume operation. A second deliberate action is needed, such as the pressing of a reset button
• Must be located at each operator control station and at any other location where an emergency stop would be required

Now, Linuxcnc has built-in software estops (halui) and estop latch (iocontrol) these components should only used for testing and simulation. Any machine larger than coffee maker that can cause harm must be equipped with an external hardwired Estop push button and a reset button.Linuxcnc ‘gate keepers’ should warn users that - software estops are not allowed - for safety sake.The only OEM that I know uses Linuxcnc software is ‘Tormach’. If you take look at their machines, they equipped their  machines with an external hardwired Estop and reset/start push buttons, the reason liability.I am only trying to raise awareness about software estop, I am not trying to spread fear or trash Linuxcnc, to the contrary Linuxcnc is an excellent piece of software. However, Estops, safety devices and watchdogs must be built external to any controller including PLC, DCS, redundant controller …

Software Estop in the form of UI/HMI touchscreen, flat panel display driven by mouse/keyboard, software commands (G code …) and membrane switches are NOT ALLOWED.

I agree but the implementation of proper machine safety standards is first and foremost the responsibility of the machine integrator. Regulations that apply in one country may not apply in another. Also in most countries machine safety regulations will go WAY beyond having a proper emergency stop push button.
Generally I would be willing to bet with anyone building a cnc machine (other than a serious commercial company) that their machine is in breach of code somewhere.

There is a lot more to safety circuits than just the estop. Safety relays, redundant circuits, timers, force guided relays to name a few. Most readilly available estop buttons are not compliant to start with.  The added cost of compliancy is a few hundred dollars and few DIYers are willing to spend the money,

So yes, safety is in the hnads of the integrator.

Let me be clear ,I am only trying to raise awareness that screen estops are not allowed.

This discussion is not about machine safety relays, devices, … etc. So, let’s not mix-up things and muddy the discussion.

This awareness message is strictly about machine estop/reset only, which require very simple relay circuit. If you cannot read electrical diagrams just google start/stop circuit and you will find several examples showing realistic picture and wiring diagram for non electrical inclined. 

To build an estop/reset circuit you need: red mushroom shaped push button, a push button and a relay wired as follows:
 

F117 has 9 computers with a single purpose of keeping it from falling like a brick!
Yes, it is a plane, and it is stealth.
No one asked for this info.....
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Benb is trying to explain, with examples, how e-stop functions and how it should be implemented and why it is very important, so help him.
Thank you Benb.
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Mentioning related stuff and the multitude of options might add to it, but it is not helping much without actual examples and corresponding info.
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Another rant:
I have never used e-stop latch, although it does have it's uses for sure, but i have used the normal e-stop in and out even on 16 ton machines, as Aciera so eloquently put it "the implementation of proper machine safety standards is first and foremost the responsibility of the machine integrator" so the e-stop from LinuxCNC is just integrated into the machine e-stop system.
My point being, stop telling people to use e-stop latch unless they actually need it, they wind up wasting days trying to set it up and get frustrated, while the machines using it can be mostly stopped with a single hand and not much effort.

Not really good enough. Everything needs dual redundancy.
 
Note that the estop button has two redunant circuits
The main contactor needs both K1 & K2 to be triggered
K3 & K4 are seperate force guided relays. Linuxcnc is not updated with a sucessful power on unless both K3 & K4 are triggered.
Force guided relays have a non conductive pin forced between the contacts to ensure contacts cannot be welded together.
Additional safety switches eg. door switches, guards etc are placed in the S33/S34 loop with the reset button.

With such a wiring layout, it is permissable to use  linuxcnc's software power button as a reset latch. In this case, use iocontrol.0.user-request-enable as it receives a pulse to repliciate the external reset button.

BUt the safety relay cost me $250 AUD and another $100 or so for the force guided relays.