Mod/Add-on to enable auto shut off of 24v-PSU?

Ottobawt

I have a D300VS with duetWiFi and a simple MeanWell 24v PSU.

What is the easiest way I can get my PSU to shut off after a print?
Some kind of relay?
Could this be made to work? https://www.amazon.ca/Iot-Relay-Enclosed-High-power-Raspberry/dp/B00WV7GMA2

I often have a print I want to start before bed, or before I go out for the day, but I don't want the PSU idling for hours on end.

Jacotheron

The way I do it:

A 24V relay module (with flyback diode etc), which gets its +24V for the coil from the PSU, which can switch the Mains to the PSU on/off (using the Normally Open connections).
In parallel to the relay I have a Main rated momentary switch, this is what I use to turn it on. Simply pressing this releases mains to the PSU which generates the 24V Vin for the Duet and turns it on (in the config.g file I have the M80 command quite early - https://duet3d.dozuki.com/Wiki/Gcode#Section_M80_ATX_Power_On).
The Negative for the 24V Relay is on the PS_ON pin. This is the pin used by M80 and M81 (the PS_ON pin becomes GND when the logic have it as ON - therefore the relay finds GND through the coils and it engage).
Finally I have a macro for switching the power off (manual method), which first asks if I really want to switch off right now (with option to move axis first) and the sleep.g file contains the M81 command (for shutting it down).

With this setup, in DWC there is an option to let the printer sleep after done (which runs the sleep.g file after the current print is done). And for normal operation, I have the Macro on the PanelDue (making it easy to switch off).

The added bonus of my method is that the Mains bypass switch does nothing when the printer is on (if someone decides to start pressing buttons, it won't kill the print - not often in this situation, but useful when I am).

The other method is supplying a different 5V (either USB or from a different PSU) to the 5V pin close to the PS_ON pin, with its GND. Then the 5V selector jumper needs to be changed to use the 5V-EXT. This runs the 5V and 3.3V logic from the secondary PSU, and allows you to only switch the 24V on, when it is needed (having the relay again inline with the mains). I am not a fan of this as the Duet keeps running unless you manually switch off the 5V.

dc42

Here are a couple of variations on the method suggested by @Jacotheron

Use a DC-AC solid state relay instead of a relay board. Connect the control terminals between PS_ON and +5V.
Use a 5V relay module, which is easier to find that a 24V relay module. Connect the 5V power input between +5V and ground, and connect the control input between +5V and PS_ON.