Auto Tuning Bed Problems

I am having some issues getting the bed to auto tune. I was able to do it in the past and don't understand what is happening now. The bed is 300x200x6mm with a 600W heater. I start the tuning with this command:

M303 H0 P0.4 S100

I get one of two situations here. Either it reports the temperature is not increasing, or the tuning continues until the max temperature is reached and then cancels. In the first case, I can see the temperature rising, but guess it is not going fast enough.

After the bed has cooled down and I try it again, I get either of the two options again. I have tried several P values and nothing changes. I commented out the M307 command that was there for the heater with no change in behaviour. I would guess the auto tune ignores those values anyways.

What is going wrong here?

Running 1.15e with DWC 1.12

Edited 1 time(s). Last edit at 11/17/2016 09:05PM by ElmoC.

Reduce the S factor to avoid exceeding 100C during auto tuning. Try 0.3. To avoid the "temperature not increasing" error, send M307 H0 D30 before auto tuning.

Edited 1 time(s). Last edit at 11/18/2016 02:28AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

The M307 H0 D30 was the trick. I had to go down to P0.2 to get it to auto tune. Thanks.