External Reset Switch
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My recommendation would be to use the external trigger to trigger M112/M999 as explained in the link because there is not another location that the reset wire is exposed.
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My recommendation would be to use the external trigger to trigger M112/M999 as explained in the link because there is not another location that the reset wire is exposed.
Thanks much - will give that a try.
Frederick
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Can someone specify a bit more in detail what is going to happen AFTER executing an M112 midprint or mid-homing or something else?
I assume, every command in the bugger is getting executed UNTIL the internal gcode buffer reached the point where M112 is listed? This way, it is more like a delayed stop?! (just assuming)
What if M112 is executed while homing? Or a long G1-move? -
M112 may be delayed a little depending on how busy the processor is. Whereas the reset button stops everything immediately and restarts the Duet.
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Does "a little" mean: "after the currently executed commands are done"? Or does the DUET interrupt mid-command?
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M112 will interrupt mid command. But until I migrate the firmware to RTOS, it may have to wait for an SD card or network transfer to complete before the processor sees the M112 command.
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Is there an "approved" place to connect an external, normally closed, reset switch?
Fredrick,
Is this intended to be a "Reset" or an "E-Stop" in the TRUE sense of e-stop? True e-stops, as found in the machine shop floor CNC world are quite rare on 3D printers.
Even if the switch looks like below, it is often wired up as a "Stop" not an "E-Stop". What is the difference?
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"Stop" signals something to stop. Most of the time, this works. However, it is easy to see circumstances where it might not: What if the firmware is off in an interrupts disabled loop, that happens to toggle one of the motor driver 'step' pins? Or whatever. It does happen…
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"E-Stop" forces it, no matter what the machine state, including totally hung software, firmware, and most of the hardware. As an example, many "E-Stop" on CNC are wired into a board with gates that inhibit the stepper driver enable lines. Pure hardware, and 'very far downstream' close to the motion.
If you want a true e-stop on a piece of hardware that doesn't have that input, here's one way to get there:
My CNC E-Stops that are on boards like the Tiny-G that did not truly accommodate E-Stop in the hardware… those E-Stop switches are wired to cut the power provided to the controller board (and motor drivers logic side, where external drivers are used). Hitting the latching E-Stop physical switch stops the machine INSTANTLY, within the realm of friction and inertia. The motors certainly do not take even one more step.
Switches like this, wired in a loop with using the NC side of the switch, with that loop providing power to the controller board:
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In the individual case of the Duet, the full power for all drivers, bed, etc, (the main big green VIN with screw connectors) should NOT pass through the e-stop loop.
Instead, set the jumper "Ext 5V EN", and then use the e-stop loop to break the 5v flowing into the separate (pin) connector (labeled "EXT 5V" in duet wiring diagrams).
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Why not fit an emergency stop yellow switch with big button in the mains supply to the machine? Or use an rcd plug placed next to the machine which has a test button, this is even better as it breaks live and neutral and offers protection from ground leaks, shorts and current imbalance all at once. If you have power fail/resume correctly setup you can potentially restart your print once the problem is resolved.
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Why not fit an emergency stop yellow switch with big button in the mains supply to the machine? Or use an rcd plug placed next to the machine which has a test button, this is even better as it breaks live and neutral and offers protection from ground leaks, shorts and current imbalance all at once. If you have power fail/resume correctly setup you can potentially restart your print once the problem is resolved.
Because cutting the mains will allow the machine to operate for several seconds. This SHOULD be a shutdown, as the board senses power loss, etc. And your point about resume is valid if everything is set up correctly.
But… that is a "Stop", not an "E-Stop". Which may be fine for 3D printers. And it is certainly your decision.
At the same time, make an informed decision: If you want true E-Stop, freeze the machine instantly, not one more step, then cutting the mains misses that mark.
