PT100 better wiring and software M305 settings

  • @dc42
    Thanks so much about taking us/me serious. I have a couple of ideas why everything is like it is:

    • metal-debris: In my case there was metal-debris in the open lower "bay" which also houses all the electronics, I learnend now the hard way why electronics should not be underneath the gantry with open top, when you are still working on your metal-gantry or even weeks later after working on it when it wasn´t cleand perfectly... vacuum-cleaning helped (and checking from time to time with the (mobile-phone-)torch/led if something glitters in the electronics-bay
    • loose connectors: I am sure in the huge build-up I made for the local artists here the long cables can pull with quite some torque on one or both of the ends, why strain-relief becomes a very important thing, so that not over time or while print-head is moving in a print connectors start to widen over time or the crimped side of the connector starts to loosen... I thought I was smart to take cables with an aditional flame-retardant layer, but so they quite thick, don´t know if I would do that anymore that way but rather buy one thick flame-retardant-flexible-tube where I put all cables for the printhead into...

    With all that said: I am too young and studied stuff too far away from that to not have to have that learning-curve. So in a sense you - meaning you - become victim of your success with your very good pcb and support because more and more novice users - like me - try to use it 🙂 in a maybe too professional intention 🙂 while not having learned the necessary precautions...

    So how to proceed with people like me:
    Since I can understand if you do not like users to be able to totally disable all faults permanently for all heaters because it would be unresponsible to have some young kid burn down the printer and maybe even more because of it, how about a stepped safety/precaution:

    • For people that know how to make connectors/cabling and to avoid metal-debris, have the full security-features like they are now or even better (default setting)
    • for the rest, maybe offer more way to loosen even more than now the boundries of M570 by widening amount of short error-persistency: So if there is a short only a millisecond or so only every x minutes, it can be ignored - at least in my case with a metalgantry printing on a metalplate. If the short is more permanently like more than x seconds with a variable to set this would be perfect (I doubt M570 Px is doing exactly what I am describing here?) there might be a more severe problem... and it should throw a fault... so somehow differentiate between a temporary problem and a more severe permanent short to "high"/"low".

    Oh and also maybe good info for the next iteration of the pt-100-board: I hooked up a second pt100 just like it came (out of the box) putting no crimp or connector or whatsoever on it to be sure that I do not change anything. Surprise, surprise. If with the old connectors (changed now) there was a heavy spike, even this second pt100 sitting near the pcb had a spike... that way I knew I did something wrong with the connectors on the cables or so because those "shocks" must have been so heavy the "spark" reached from one pt100 to the next one or it might even come via the pcb.

    Since avoiding after each connector to make a test but rather redo all connectors and starting up the duet, I cannot say which connector was the worst, just that definetly it was my fault 😞 so thank you even more for your help 🙂


    EDIT: Ah - a friend of my suggested the following: Since it is possible in config.g to hook-up additional virtual sensors -> Why not be able to config another virtual heater-sensor optionally which shows the raw-data of the temperature-sensor! That way when wiggling on a specific cable I might have a clue which cable/connectors to track down without borrowing an oscilloscope and learn how to use it...

    EDIT2: Spontaneous idea e.g. Within M570 an additional variable like Fnnn with F0=cancel print even with non-persistent but beyond threshold heater fault F1=pause print with non-persistent but beyond threshold heater fault F2=only issue permanent M117 message but keep printing with non-persistent but beyond threshold heater fault -> what is persistent and non persistent could be defined within M570 Pnnn/Tnnn variable?
    I gues in this scenario F2 is too risky? Or would this interfere with the M143 Annn-set? Better to put it there? How to correlate M570 to M143?

    EDIT3: Will check PCB soon, hopefully saturday if any connector has gone loose


    EDIT4: My poor qualification for those connectors with special crimps is why I asked some time ago for those simple (round-crimped) push-terminals on the pcb´s that wago, phoenix-contact and the taiwanese company that I forgot the name of (JVC) have in their portfolio. But that said/written, I could understand that you cannot choose your connectors by the poorest performing customers 🙂


    EDIT5: One thing for future that could be beneficial for next iteration boards: Of course electronics on pcb´s is miniaturizing more and more, but the connector´s on the user-side/interface-side could still be big & have a decent distance between each pin (2,54mm...) for not so talented users like me to make sure when I "assemble/make" that connector to my cable the possibility of only one fine "metal-hair" of the unisolated cableends of one pin to the next pin within one connector, has a low possiblity to touch each other because they are well separated. Also I start to hot-glue all connectors when they are assembled, that because of movement, they cannot become loose over time. Just one other fine detail... I can see the problem that too big connectors take up too much space on the pcb

    Oh and EDIT6: One major problem was my own "home-made" cable to the paneldue. Since that cable is 3meters long I bought one with ca. 0,5mm^2 diameter and very good shielding ... and it works of course ( 🙂 ) but I was not carefull enough with those connectors and have to redo them definetly (at least there is ca. 30cm still too much cable so I can chop off another bit and redo them...) When I unplug it 99.9% of all spikes are gone, only that 1 every half an hour or so. If I can find that last connector I am not sure - rather I gamble on your next firmware-update I guess 🙂

  • @dc42


    Please, is there any recent advice to retrofit capacitors on the PT100 daughterboard because of H1 heater faults ? I have such a PT100 daughterboard bought during 2019 along with Duet3d wifi and Delta Smart Effector+PT100, and am having my share of H1 faults.


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