Have a printer with inverted runout sensor

I have a 3d printer and no marlin config to recompile the firmware.
Is there a way to invert the pause signal from the sensor in octoprint so it does the oposite?

Soo stop when it should go and vice versa.

I tried all plugins i could find but all are for the rb. pins.

My only solution for now is to plug the sensor out.

which sensor is it?

And what sensor plugin?

All plugins (Filament Sensor Simplified, Octoprint-Smart-Filament-Sensor etc..) are made for RBI i run octoprint on docker in my server. My run-out sensor is connected to the BIGTREETECH SKR 2 board... but the old runout sensor was inverted.. now it sends inverted commands.. ~~`
And i cant recompile it miliy nilly because i have no way to compile the exact config. And this one works really well.


Does the sensor have a way to change the wiring to it? If it is a limit switch, they typically have 3 connections. Common, Normally open(NO) and Normally closed(NC). Changing the connection to the NO or NC connection points would essentially invert the signal.

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no it is an inductive type. if it would i should, but it cant so i rant :smiley:

Well if you cant do it in the software... You could do it with hardware.. Use a relay with both NC and NO contacts.. Have the sensor drive the relay. You can now pick which way you want it to be active.

Good luck.

Can you tell us the type or at least send a image?

yes my point is i want to do it in software.. not hw. Its a pain in the ass to take it apart.

The software solution is to compile a modified version of the firmware. If you won't or can't do that, then a hardware solution is your only other option.

Marlin is licensed under the GPLv3 and is free for all applications. Contact BigTreeTech (https://biqu.equipment/) and request a copy of the Marlin firmware sources for your board.

One hardware solution that hasn't been mentioned is to attach this hardware sensor to the Raspberry Pi instead of the SKR 2 board.

Another alternate plan would be to replace the "old" runout sensor with an identical one.

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Or you could just look at what they have published out there already: https://github.com/bigtreetech/SKR-2/tree/master/Firmware/Marlin-bugfix-

It's also worth noting that the BTT SKR 2 board isn't generally stock in any printer, so even that source above isn't going to be that helpful in this case. That also means that someone had to have built the firmware for this particular printer at some point as well. If it's something that users commonly put SKR boards in, there's likely an example configuration out there already: https://github.com/MarlinFirmware/Configurations/tree/bugfix-2.1.x/config/examples