Two thermisor on chamber and limited heater

Deez3443

Hi,
I am using Duet2 wifi and RRF 3.3.
I want to configure a heated chamber with a 200W heating mat. The heating mat is limited by the thermistor and the chamber thermistor is higher. I set it up this way, but it doesn't work.

M308 S0 P"bedtemp" Y"thermistor" T10000 B4138
M308 S3 P"e1temp" Y"thermistor" T10000 B4138
M950 H0 C"bedheat" T3
M307 H0 B0 S1.00
M141 H0
M143 H0 S50 T0 A2 C0 P0

In DWC I have options to choose the chamber temperature and in the "extra" tab I have temperature. When the chamber temperature is set 50, the temperature in the "extra" tab increases indefinitely. According to the configuration, it should stop at 50C. Am I doing something wrong? The heater is connected to the bedheat, the thermistor to limit the heater is bedtemp and the chamber thermistor is e1temp

infiniteloop

@deez3443 The thermistor resistance looks a bit low: 10k? - 100k is common. Please verify this.

Then, I miss the heater of the heated chamber. It should be defined with another M950.

Third, you assign the second thermistor #3 aka "e1temp" to your bed - is this intended? What happens with thermistor #0 aka "bedtemp"?

Forth, you might want to have your bed thermostatically controlled: this has to be tuned, the resulting values must then be set with M307. Currently, you just let your bed happily heat up with full power.

If you are not sure what to do, clarify which hardware you have connected to which ports and what you intend to do with it. Finally, please post your complete config.g.

Deez3443

@infiniteloop ofc. 100k is correct value,I was copying these lines from screenshot and made a mistake.
Yes i use my e1temp to control chamber temp, and my bedtemp to control my heater (like thermostically control) i try limit heater temp by M143 like on this link.

Example

You have heater 3 mapped to a chamber heater which is supposed to be temporarily turned off when the temperature in it exceeds 65C. The thermistor for the chamber is set up as a virtual heater on channel 104 and can be viewed on the "Extra" panel on DWC (refer to M305 for further details on how to set this up). To achieve this you can configure an extra heater protection with the following gcode:

M143 P100 H3 X104 A2 C0 S65

But in RRF 3.01RC2 and later parameters on M143 have changes.
I use this hardware settings becouse i dont have heatbed.

Hardware settings.
Hotbed socket - heater
Hotbed thermistor - thermistor phisicaly touch heater
E1 thermisor- thermistor 200mm away from heater

I want use my hotbed thermistor to limit temperature on my heater and control chamber temperature by E1 thermistor.

infiniteloop

@deez3443 Here's an example of how it works:

M308 S0 P“bedtemp“ Y“thermistor“ T100000 ; define thermistor #0 as contact sensor for chamber heater
M308 S3 P“e1temp“ Y“thermistor“ T100000 A“chamber temp.“ ; thermistor #3 monitors chamber temperature
M950 H0 C“bedheat“ T3 ; heater #0 (chamber) gets coupled with thermistor #3

M307 H0 Rx Cx Dx B1 ; <<< here, insert tuning parameters R, C and D

M141 H0 S-273.15 R0 ; heater #0: initially 0 degrees, off
M143 H0 T0 A2 C0 S150 ; shut-down heater temporarily if exceeding 150 degrees (change S as needed)

NOTE: you should try to tune the heater in order to get useful values for M307 (see the link in my post above). Given the low wattage of your heater, this might be tedious or even impossible - in the latter case, you should narrow down to reasonable estimations. However, don't take this easy, "generous" values impose a security risk.

Deez3443

@infiniteloop Thanks you for example, I will test it tomorrow and write about the results.

I know, 200W its to low but this is only test setup with small chamber, ultimately setup have more power.

Deez3443

Initially, everything works. But not in the case of the M303, when using auto tuning, even M143 is turned off and the temperature of the heating element rises "endlessly". When entering initial PID parameters, and simply setting the chamber temperature, M143 works fine.
Do you have any idea how to use autotune correctly in this system? At best, I will set it up manually.

infiniteloop

@deez3443 said in Two thermisor on chamber and limited heater:

Do you have any idea how to use autotune correctly in this system? At best, I will set it up manually.

Given a 300W chamber heater, I had no luck with autotuning. Temperature rise was simply too slow. In the end, I figured out parameters that gave me just some rare heater warnings - they indicate, at least, proximity to a proper model of the heating process.

Finally, I enhanced the fault tolerance with M570 H3 P300 T25, as my heated chamber is (due to the weak heater) quite an inert system. However, you might wish to use other parameter values.