Im using a mains heated Silicon matt on mine.... Ive put three levels of protection and control. A mechanical relay, that would fail open (ie off)
This is the the first layer, this is triggered by PS_ON, PS_ON will also kill power when thermal runaway is detected in software. This could happen if a therm has failed or if the SSR fails and is stuck on, The actual PWM power control is done by the SSR from the heat bed pin.

Using an SSR for the PWM protects the mechanical from wear, as these are designed to have fast power cycles, its basically a power transistor...

After that, a thermal fuse on the bed, if the software crashes and for some strange reason PS_ON is stuck on and heat signal is also stuck on (very unlikely but in the realms of possibility) the fuse will trigger when the temp hits around 140 with the fuse ive got.

So in this setup its incredibly unlikely a mains heat bed will cause a fire. Im also thinking of just adding a power fuse in the line as well to protect against possible shorts if anything damaged the power line in there... Though there is going to be 2 fuses, one on the kettle socket and one in the plug socket...

I was just thinking a lower rated fuse just for the bed. maybe 4 or 5 amps... My bed is 3 amps max... So anything above that would be a short or something else failing...

I had this issue just recently, it's not very clear what goes where...

Anyway I found this guide
https://www.instructables.com/id/Wire-Up-a-Fused-AC-Male-Power-Socket/

With mech relay working, having to manually do m80 m81 to trigger it... but my keenovo heater is heating up nicely

Now all i need to do is tie M80 to trigger when the bed is set to active... and M81 when the bed is set to off and in thermal runway detection...
How

So ive just noticed that when browsing the system file list in the config, the web page snaps to the top of the page while scrolling down the list.
Im assuming its happening when the temps update their figures in the main UI up top.

Is this something in the webpage design? or is this something going on in my browser causing that?

Is this a bug?

Does it happen with anyone else?

Ive not tested it with the gcode file list yet. But ive not filled that list up with anything really... but I can imagine it becoming very tedious while searching for a file through the list only for it to snap back to the top every second or two...

Thanks
s-1 wasnt listed on the doku gcode wiki... the reprap gcode wiki did mention it but as a delete all triggers option...

Anyway its sorted now thanks

I have read the docs and maybe I'm blind I can't see anything about canceling the previous trigger?

@dc42 Oh how do you cancel the old one?
I had assuming the new trigger declaration would over write the old one...

Ok having a problem...

At the end of my config file I have

M106 P1 S1 ;Turns lights full bright
M581 T2 E3 S0 ;Light switch

trigger2.g
M106 P1 S0.66 ;Turns lights 1/3down
M581 T3 E3 S0 ;preps next trigger

trigger3.g
M106 P1 S0.33 ;Turns lights 2/3down
M581 T4 E3 S0 ;preps next trigger

trigger4.g
M106 P1 S0.0 ;Turns lights off
M581 T5 E3 S0 ;preps next trigger

trigger5.g
M106 P1 S1 ;Turns lights Full on
M581 T2 E3 S0 ;preps next trigger

The lights will cycle down once and back to full bright as the button is pressed. But trigger5, the prep next trigger doesnt seem to work.

So i press the button from fresh restart, turns down 1/3 press again turns down another 1/3 press once more turns off, press again and turns on full bright, but pressing again does nothing. The lights would briefly flash off but isnt cycling down again.

Am i missing something?

Actually that sounds reasonable.... Thanks

Yeah I've been reading that already. That's fine for setting a state with a single button... Like an end atop or emergency stop. But I would like the ability to cycle through two states or more.

Is there any kind of expression system that can be used?

So I have my printers lighting setup on Fan channel 1 (0 being primary fan)

Now I would like to set a momentary button to turn the leds on or off. Or even if possible several stages of brightness.

In c it would be something as simple as changing the state of a boolean light!=light;

But is it possible to make a trigger do a if statement? If fan1==0 ; fan1=1;... type thing? Or toggle a boolean?

Can complex scripts be stored in the .g config or trigger.g files?

I must say this thread was a fun read.... Congrats on fixing your board.

Like i mentioned in my case, I do have passive and active protection going on... There is a thermal fuse in line with the heater bed so if that fails its obviously cutting power... But having software controlled stuff that could save me a fuse and is free that would work 90% of the time. Why not?

So for people like me who have a mechanical relay as a first gate for the mains powered heat bed, having the option to shut off the power via any IO, (ps_on just happens to be the one used as thats what seems to be recommended at the time) would be hugely beneficial.

Simply put, you cant have enough safety.

Oh and I have that 700 w keenovo matt. So I think i read it tops out about 250c...

The only safety feature I haven't done yet is earth the frame of my printer.... Must do that...