Relais to power of the Printer

[MauriceM]

Hey, I would like to be able to switch my printer on and off via a relay.
I already have the relay here, it needs 5V and GRND which I would take from the exp header.
Also use a Duex5 so all pins on the bar are omitted.

Which pin can I use to tell the relay to always send a signal as long as the board is on (to keep the relay open) and if any error message comes in, to stop the signal to make the relay close.

[BoA]

@MauriceM PS_ON can be used for that.

[MauriceM]

Thanks

how do I configure the pin that does this, maybe someone can explain it to me

[alankilian]

This page talks about using the PS_ON signal and an external relay:

https://duet3d.dozuki.com/Wiki/Power_Wiring

If the main PSU supports an ATX-style PS_ON pin (power supply on when pin is connected to ground),
the Duet 2 can enable and disable the main power as needed. Obviously this will not work if the only source of 5V
is the 12/24V circuit you are switching; you must either supply USB power or use the 5V in pin from a supply
that is not shut down when the 12/24V supply is. On an ATX power supply which provides this function.
 
If you are using an external relay to control mains power to the PSU, you can wire either the +5v or +3.3v
(depending on what your relay requires) outputs from the duet in to the positive terminal of the relay, and wire
the ground terminal of the relay to the PS_ON output on the duet. If you are using a mechanical relay and it
does not include a flyback diode of some sort, you will need to wire one in parallel with the relay signal.
 

[MauriceM]

sry i expressed myself a little wrong, i know how to wire this, otherwise i would not do this
But my question is more like writing a script or something, that the PS On Pin is always on as long as the board has power and goes off when any error comes in

[engikeneer]

@MauriceM You'll probably be wanting the A parameter in M143:

https://duet3d.dozuki.com/Wiki/Gcode#Section_M143_Maximum_heater_temperature

Going for A1 will trip the PS_ON if it gets a fault (I believe but haven't yet tested myself). You'll need to set this for each heater.

Not sure if there are any other errors that you would want to kill power for?

[MauriceM]

na only the heater error, or short to ground in case a cable breaks inside the cable chain or something... but i thunk that the heater faults are enough.

[MauriceM]

ah ok that makes sense also i think A3 will work also ...
I will try it

[MauriceM]

ok this works fine, i will do that for all heaters, now i have to figure out how to do this, for example when a thermistor wire breaks,...
Even if the printer is cooling down i want to shut off the Power

[BoA]

@MauriceM Not sure if this is a good option. RRF will shut heater down, but I would prefer to keep cooling, otherwise You can end with melted extruder parts near hotend due to fan turned off.

[MauriceM]

there is everything printed out of PA12+cF15, i dont think that this will melt.
I rather have a safe printer.
But i think this should be enough at first, i only cant get to shut off the printer via the chamber heater... but i think the other 3 will be enough

[BoA]

@MauriceM Well... if You turn off cooling on hotend that has 280*C... I am not sure... PA12+CF15 can hold something like... 150 - 160 *C?

[MauriceM]

ah i thought about the fan ducts and not about the heat creap, yeah that could be not so nice....