Setting up heater chamber - need help

felt342

@JoergS5 I just did a test and got now this error with 0.3C/s

Error: Heating fault on heater 5, temperature rising much more slowly than the expected 0.3°C/sec

Could be what my value for E3D thermistor are wrong? But those values is something that I found on duet forum for e3d thermistor.

JoergS5

@felt342 can you see how 1.7 and 0.3 is calculated? M307 original and now)?
I found the error message in the source code, it depends on expected rate, dead time, the current temperature and the PWM.

Measuring the temperature wrong could be a reason.

I've also seen 4725 as value for the E3D thermistor. You could try verifying that it works by heating up somehow without the chamber heater. (hair dryer)

felt342

@JoergS5

Well, setting C value to 2000 doesn`t give me an error anymore about Fault in heater 5, and its keeps the rising temperature. But I still can not do the autotune.

Yeah the thermistor seams works.

JoergS5

@felt342 you get the same autotune error like in the first post? And does the reported temperature value of the thermistor go up?

felt342

@JoergS5

Yes, this is an error:

Autotune canceled because the temperature is not increasing.

Temperature goes up, but slowly about 1 degree a minute. This would be fine for me because I am planning to add two heaters there overall of 600, but first I got one and would like to deal it up first, to at least heating without errors. Which we did now (thanks to you!) setting C to 2000, but to perform autotune for real values would be better.

JoergS5

@felt342 Seems to be a timeout. I cannot find the error message in the source at the moment.

felt342

@JoergS5

Yeah, I really appreciate your help and digging in! What I am thinking is maybe better to move thermistor to the middle of the chamber, it will probably be the faster response until I have only one heater.

JoergS5

@felt342 Now I know why I cannot find it. I search in the 3.1.1 code....

=> didn't find it in 2.05 code also. Will search and will tell you if I find something.

felt342

@JoergS5

Happens
Thank you!

JoergS5

@felt342 I found it in pid.cpp of 2.05 source:

// Heating up
{
const bool isBedOrChamberHeater = reprap.GetHeat().IsBedOrChamberHeater(heater);
const uint32_t heatingTime = millis() - tuningPhaseStartTime;
const float extraTimeAllowed = (isBedOrChamberHeater) ? 60.0 : 30.0;
if (heatingTime > (uint32_t)((model.GetDeadTime() + extraTimeAllowed) * SecondsToMillis)
&& (temperature - tuningStartTemp) < 3.0)
{
platform.Message(GenericMessage, "Auto tune cancelled because temperature is not increasing\n");
break;
}

So the error message is called and a break occurs, if the heating time is bigger than dead time + extraTimeAllowed.

A low dead time helps in any case.

extraTimeAllowed is defined by:
const float extraTimeAllowed = (isBedOrChamberHeater) ? 60.0 : 30.0;
so for Chamber it is 60.
You could try setting D negative, say -59. Don't know whether it works.

You're welcome and I wish you success with the heated chamber!

felt342

@JoergS5

That seems working without error!
I didn't try negative D, but I set D to 1 and kept C at 2000, waiting for autotune and values

Thanks a lot again!

JoergS5

@felt342 Nice to hear, thank you!
See you.

felt342

@JoergS5

I must say it`s a nice way of solving the issue, digging the source code, will take it as a tip