Filament Runout Pause with Printer built in sensors

I am using a Formbot T-Rex 3.0 that I currently have Octoprint hooked up to. It appears to be working correctly as far as I can tell. The T-Rex 3.0 has filament runout sensors built in, and I was wondering if they would work with octoprint to pause the print. I have not tested running filament out if it does or not. I was wondering if the octoprint would just keep sending commands to the printer and if the printer would not notify the pi to stop sending gcode.

It's really going to be dependent on the firmware that the printer is using. If the filament runout sends an action command back to connected clients (like octoprint) that a pause has been done, then yes, OctoPrint will actually pause as long as the bundled Action Command Prompt Support plugin is not disabled.

Careful, the quoted plugin is for specific action commands that control prompts. Regular pause, resume and cancel commands are always supported. The firmware just had to send a pause command on runout. A prompt offering to resume after fixing the issue would also be nice and possible, but it is very unlikely the firmware implements that already.

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Hi @tbase9
Would you mind sharing your profile for your T-rex 3.0?
I just bought one myself and a new raspberry is on its way :slight_smile:

I'm also having trouble finding info on the T-rex, such as more technical info and other users and so on. Do you have any suggestions on where I may look?

I'll investigate the next days. Got my T-Rex 3 today and currently setting up a RPi for OctoPrint.

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Thats great :slight_smile:
I got mine two days ago and I'm very happy with it. Guess I'll have to wait for the RPi until monday :frowning:

Looking forward to hearing from you

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I just verified: it does.

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Hi Ewald,

I am recieving a T-Rex next week and wounder if you have any tips and tricks. I just installed Octoprint on a RPI 4B and did all settings >I could at this stage.
Did you have to do anything special while setting up the printer and/or in the settings in Octoprint?


Hello @rippe!

The T-Rex 3 runs fine with OctoPrint.

You may do this: Put tape on the 5V pin - Why and how, because the printer board draws current from the pi.

I'm using PrusaSlicer for my prints. Here are the profiles I use: (7.9 KB)

The OctoPrint printer profile is just to filled in with the printer parameters.

But first follow the printer instructions for assembling, calibrating and test run.

Hi @Ewald_Ikemann,

Thank you so very much for sharing all these settings and information. I have installed PrusaSlicer with the files you provided and are now just waiting for the printer...


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