Heater Fault - No Error
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My printer is controlled by a Duet3 with a toolboard (v1.0). I have used M303 to tune the hot end heater a couple times. Its a Dragon hot end with a 50 watt heater. If I use the following tuning with 100% PWM I get a heater fault at about 50-60DegC but no error shows in the console.
M307 H1 B0 R2.436 C284.6:199.0 D7.35 S1.00 V23.9If I use the following tuning with 80% PWM I don't get the fault.
M307 H1 B0 R2.314 C340.3:340.3 D9.18 S0.80 V23.9So I can certainly live with the 80% tuning but it seems very odd to get a fault and no error. If I reset the fault and continue heating to 120C (my probing temp) the heating continues with no fault. I never get a fault heating from 120C to printing temperatures. I suspect there is some heating rate limit for safety and at 100% my printer exceeds that limit. A 50 watt heater may be overkill for this hot end. I do get the possible over temperature warning when starting up or executing the M307 commands.
Any Idea what causes the fault?
Board: Duet 3 MB6HC (MB6HC)
DSF Version: 3.3.0
Firmware: RepRapFirmware for Duet 3 MB6HC 3.3 (2021-06-15)John
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@wifibeagle I've no idea if this is related to your problem, but there is something a little odd going off with those two sets of configuration values. The first has two very different C parameters (for cooling fan off/on) in the second they are identical. Did you do the PID tune in the two cases in different ways? Perhaps one using the tool number (which would use the fan) and one using just the heater? Either way it looks like your part cooling fan may have a big impact upon your heater rate, is it on/off when you get the fault?
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I should have noticed the difference in the C parameters. I guess I focused too much on the R parameter. The part cooling fan is always off during initial heating which is where the fault occurs. I have made some modifications to the part fan nozzle so I should have redone the auto tune. I will watch carefully to insure the part fan comes on during the tune.
Thanks for the suggestions.
John