Emergency Stop function and terminology discussion
August 27, 2019 03:47PM
Figured id shine some light on a discussion over on the Marlin GitHub right now since it applies pretty generally to every firmware and some slicers.


Essence is ive proposed changing the name from Emergency stop to Full Shutdown or system halt, or some similar message. In many regions, Emergency Stop is regulated with the use of fail safe hardware behind it, which these systems simply don't meet. The term communicates a false sense of system safety and security and could land someone in trouble with liability issues if there is a failure to shut down the system completely for any reason.

Feel free to chime in here or there. Id like to hear from developers of other firmware's as well!

Edited 1 time(s). Last edit at 08/27/2019 04:05PM by InsanityAutomation.
Re: Emergency Stop function and terminology discussion
August 28, 2019 01:50AM
I would be happy to rename it Immediate Halt or something like that in RepRapFirmware.

Edited 1 time(s). Last edit at 08/28/2019 01:50AM by dc42.

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Emergency Stop function and terminology discussion
August 28, 2019 08:54AM
Sounds good!

BTW, I havnt checked in awhile, but did the Slice Eng 450c thermistor on youre web configurator ever get updated to the correct values? Last I had checked it they didnt match the datasheet.
Re: Emergency Stop function and terminology discussion
August 30, 2019 12:51PM
In the US at least as per NFPA79 for Industrial Equipment, an Emergency Stop requires a few things including being reset before machinery can resume, power being removed as fast as possible from the machinery, and be initiated by a human action.

This doesn't require any special safety rated device, although is generally used with such devices.

And, of course this is pertinent to industrial machinery. Where does a Reprap printer or a purchased kit or some other 3D printer get categorized? Is it considered industrial machinery, commercial machinery, hobby machinery, etc... depending on how the machine is categorized depends on how these rules get applied.

I suspect this is true in every country as I've never seen one specification to cover industrial machinery, commercial machinery, and/or hobbyist machinery.
open | download - NFPA79_Excerpt.pdf (241.1 KB)
Re: Emergency Stop function and terminology discussion
September 14, 2019 10:03AM
Alot of that depends on the risk assessment level of the machine. There are more regulations around specific types of machines, OSHA regulations in different industries, and probably more factors I dont even know. With PLa and b redundancy is not required. If the risk assessment is PLc or above then it is. Regardless, firmware has no way of knowing and shouldnt make the assumption it meets that. In my opinion small machines are between a and b really as the hotend in theory is capable of a permanent injury should it pinch a hand into the build plate while heated (eg during homing). Build a bigger or higher temp machine, you can approach where it absolutely is required.

Seeing more of these machines in industrial settings just brought the question around more often. Yes there are plenty of machines that it can count as an emergency stop. There are also ones it cant. As a controls engineer Im definitely the most familiar with automotive spec safety regulations and what gets applied there, but im sure theres other applicable bits that I may not know. Regardless I still feel this is the right way to go as it does not give a false impression.
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