Duet2 high Heat Protection
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For what it is worth... having the same processor that PWMs a heater also monitor that heater seems to be a non-viable safety plan. Processor hangs (completely) and happens to be in a PWM ON part of the cycle. Oooopsie.
I am a huge believer in simple mechanical fail safe. A fusible link (or self resetting) in series with the power to the bed heater. Etc. etc. A fireball (automated extinguisher) sitting on top of the printer. Etc. etc.
So, yah, pursue this, nifty idea. Just don't make the mistake of thinking it (alone) makes anything safe.
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@Danal
I don't disagree. I like the idea of the printer turning itself off as one method of protection. Duet2 already has a few built in protection features, and this would just be one more. If I can find an external feature that would protect from the nozzle and bed heaters I would do that too. But so far haven't had any luck. The main annoyance I have had is not being able to find a proper thermal fuse for my setup. The external sensors with auto off plugs I have seen don't go over 100c.Using the duet2 board's own thermal sensors so far is my best and maybe cheapest option to setup. The more layers of protection I can add the better.
I currently have two fire alarms in the room, and a fire extinguisher at the door. -
@BlueDust said in Duet2 high Heat Protection:
@Danal
I don't disagree. I like the idea of the printer turning itself off as one method of protection. Duet2 already has a few built in protection features, and this would just be one more. If I can find an external feature that would protect from the nozzle and bed heaters I would do that too. But so far haven't had any luck. The main annoyance I have had is not being able to find a proper thermal fuse for my setup. The external sensors with auto off plugs I have seen don't go over 100c.Using the duet2 board's own thermal sensors so far is my best and maybe cheapest option to setup. The more layers of protection I can add the better.
I currently have two fire alarms in the room, and a fire extinguisher at the door.have a look at these (and some of there other thermal products
Doug
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@BlueDust said in Duet2 high Heat Protection:
How many mA can the PS_ON pin put out?
That's in my bookmarks
https://forum.duet3d.com/topic/2108/ps_on-usage/2
For the exact rating you would need to checkout the schematics for mosfet used, then check it's specs out. Certainly enough to drive a small relay, you will need to add a flyback diode to it too.Disaster? The original Printeye is dying with RRF 3.5 (M208 depreciated).
PrintPy2024 to the rescue!
MicroPython based; with simple wiring and and no custom PCB. -
If it's a mechanical relay without a driver and you drive it from the PS_on pin, remember to use a flyback diode across the relay coil.
Duet WiFi hardware designer and firmware engineer
Please do not ask me for Duet support via PM or email, use the forum
http://www.escher3d.com, https://miscsolutions.wordpress.com -
Something I forgot to mention... My main purpose of this is to catch a failed SSR for my heated bed, but if able able like to monitor/enable it for the hotend as it gets 5 times hotter...
The Duet2 locking up is a different concern altogether.
I might be able to have a RPi ping it, and possibly also interfere with the relay... Sounds like it should be an additional relay.Maybe open up the Duet2 for file sharing/ftp and setting up a RPi to constantly check the error log file for specific words. Say over heating, or temp sensor fault etc... Cut power... And if 30 seconds go by and it can't access that file to also cut power.
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@BlueDust said in Duet2 high Heat Protection:
Maybe open up the Duet2 for file sharing/ftp and setting up a RPi to constantly check the error log file for specific words. Say over heating, or temp sensor fault etc... Cut power... And if 30 seconds go by and it can't access that file to also cut power.
An external monitoring system will add a layer of reliability. Some thoughts:
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A Pi will certainly work, but seems kind of expensive given newer alternatives. An ESP8266 would also work, and are about $4 or $5 USD when purchased qty four from Amazon. Maybe cheaper, with some research.
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I'd check the http://printer.ip.or.name/rr_status?type=2 and parse out the various temperatures. Avoids FTP, SD reads, etc, etc. As you said, no response for a set time, kill it.* I have an ESP based Duet monitor that displays stuff on a 1.x inch OLED... that code could be modified to do this, very easily. I'll happily share (I really should put it on Github).
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And, just to poke fun, what monitors the monitor?
*I'd mount the little monitor on the printer frame, with an "override switch", toggle switch, so that the darn thing won't kill it when your doing various kinds of maintenance.
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@Danal
I monitor the monitor!First, I have a lot of RPis just laying around. And as I would like to use Python (to make me learn it)... Saying that, I have also wanted to be alerted via text/email when a print has an issue/pauses, or completes. If I use a RPi, I could have it search for many different word combinations and send me actual alerts too. This leads into future projects of building my own smart own. If I do it that way, it would actually be the start of a larger project, and done with a larger project in mind and built using IOT standards. And not just a one off to complete a single project.
I have some more to think about now...
Thanks @Danal! and yes, I am curious about your code, but wouldn't be able to review it this week.
Fun, that 3 letter word with "u" in the middle.
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@dc42
Should a SSR or a mechanical relay be used for this sort of thing?
As it will be either on or off for long periods of time (not constantly switching) and have 120v 15 amps running through it, I assumed it should be a mechanical relay. -
@BlueDust said in Duet2 high Heat Protection:
@Danal
I monitor the monitor!Yeah, I kinda figured. Makes a little display worthwhile. Or at least some LEDs.
First, I have a lot of RPis just laying around. And as I would like to use Python (to make me learn it)... Saying that, I have also wanted to be alerted via text/email when a print has an issue/pauses, or completes. If I use a RPi, I could have it search for many different word combinations and send me actual alerts too. This leads into future projects of building my own smart own. If I do it that way, it would actually be the start of a larger project, and done with a larger project in mind and built using IOT standards. And not just a one off to complete a single project.
Understood. With respect, I will note that ESP8266 and ESP32 are the current "darlings" of IOT, and can be programmed in Python, and send email, and, and, and... ok, I'll quite now (not really).
Thanks @Danal! and yes, I am curious about your code, but wouldn't be able to review it this week.
No prob. Maybe this will motivate me to put it on Github and write up the project on my blog. Which I've been neglecting. Of course, the Duet monitor sits in a 3D Printed case. Gotta put the STLs out there too... It has an 18650 battery. So you can haul it around with you. (Another advantage of the ESP series; you sick of hearing that yet?
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