Where do I find the over-heat trigger-level?

2.1.1 Marlin and Arduino IDE.

I have an occasional problem during heat-up where it shuts down with a run away heat message.

I have the print temp at 200 and watching closely during heat-up, the PID lets it sometimes get down to 190 and it triggers. If it doesn't go below 191during that first heat cycle, it heats OK then runs fine.

I have done a few PID settings (M303 ...) between 200 and 220 but it still sometimes drops to that 190 first time around

I am guessing there is a setting within Marlin for a 10-degree difference but danged if I can find it. I found one setting

TEMP_SENSOR_REDUNDANT_MAX_DIFF 10

and changed that to 15, but no help.

In configuration_adv.h "If you get false positives for "Thermal Runaway", increase THERMAL_PROTECTION_HYSTERESIS and/or THERMAL_PROTECTION_PERIOD".

Quote
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THERMAL_PROTECTION_HYSTERESIS
and/or
THERMAL_PROTECTION_PERIOD

Thanks, but that has not helped. It seems to be dependent on an exact 10-degree difference.

Watching the temp closely with the BTree touch screen that updates by the second, it triggers the instant the temp drops to 190.

Edited 2 time(s). Last edit at 12/04/2022 08:50AM by boolPool.

Just tested using the hotend manual option to heat and that seems to be a bang-bang thing as it runs all the way up to 200 without any PID-looking temperature display. If I then run the part it prints fine.