Hotend PID tuning stuck at equilibrium temperature

[tetele]

Using RRF 3.2. I tried to tune my main print head using M303 T0 S260.

As it turns out, when placed close to the bed and with the part cooling fan at 100%, my hotend can only reach ~240 degrees. I did it in this configuration because of some advice I received that you should tune the hotend in approximately the printing position, although I'm not sure that's accurate.

As a result, after having reached the requested 260 degrees, after settling, in the "fan on" phase, the hotend reached a steady ~238 degrees and just stays there for about half an hour, without any way for me to cancel the tuning except for resetting the board.

I would have expected the algorithm to realize the fact that it can't reach the requested temperature with the fan on, just as it does when the fan is off.

[dc42]

Thanks, it looks like we should introduce a timeout for heating back up to temperature in that phase. Note to implementor: when tuning a heater on an expansion board, it's probably simplest to do the timeout on the main board.

[mydevpeeps]

Could we have it recognize an already defined M570 code?