PID tuning with bed at different voltage.

Dkos

Hello people,

So, i finally found some time to play with the printer again and I made the switch from 12V to 24V system. Although, for budget reasons i decided to not buy (for now) a new heater for the bed. I am currently running the bed on a 12V 200W silicon heater. Therefore I kept my 12V psu and it is now dedicated for the bed heater (350W psu for a 200W heater but whatever..).

Now in the process of tuning everything to the new 24V i gave another shot at the PID tuning of the bed heater as well, but after the tuning is complete it is reported that the tuning voltage is at 24V instead of 12V that the bed is still running.

I would assume that the Duet does not know the actual voltage? (negative goes to Duet and positive goes directly into the 12V psu).

My question is, is this just an info printed by M307 H0 that i should not be worried about, or does it hint a mistake/problem?

Thanks in advance!

Edit: Board info: Duet 2 Wifi on firmware: 2.05 (I should probably update soon ).

Veti

just remove the V paramter from the command

Dkos

First thanks for the reply.

I would assume that you are referring to the M307 command which is the only one I can see to have a V parameter. I should have probably added the tuning command I used. Nonetheless this is it:

M303 H0 S110
M307 H0
M500

As far as I understand, in this scenario the M307 only reports the current settings, does not set new ones. A quick deduction would be that it automatically sets the voltage to the Duet running voltage level. If that is true I could do actually the opposite and manually set (in .config-override) the V parameter at 12V or removed it as proposed. But what would be the effect of this? M307 comes post-tuning, so as far as the PID tuning is concerned it would not matter whether the Duet correctly assumes the voltage of the bed?

Veti

https://duet3d.dozuki.com/Wiki/Gcode#Section_M307_Set_or_report_heating_process_parameters

if you dont set it its set to 0 which disables the voltage adjustment

Dkos

So I deduct that the process of PID tuning itself (M303) is not affected but what voltage the Duet thinks the bed is on.

Nonetheless I did as suggested and disabled the psu voltage compensation. l am keeping the rest of the PID values as they are.

Thanks for the answers!