Adjust M305. What am I missing?
after read all info that you have pass me in previous post... and try with little success adjust. I have done a test area.
Although now I am very close, or at least more than before, it does not end well. I put here the method that I have used, so that you tell me that it is wrong, or that I can do better
What have used:
- Old heatblock
- 50W 24v Heatcardrige
- Termistor (for control heatcardrige), now T1
- Termistor, that i want configure in DUET, now T2
- Kitchen termometer, only reach 250 degrees
01- First drill in old chinesse Volcano heatblock a hole for T2
02- Mount in heatblock
02.A- 50w 24v Heatcardrige, connected to DUET
02.B- Termistor, T1. Connected to DUET
02.C- Termistor, T1. Conected to Multimeter
02.D- Kitchen termometer, in nozzle hole
03 - Power on Duet, and connect to DWC with a PC
04 - I measure the temperature and the resistance (with Kitchen termometer and multimeter), at rest.
Real temperature = 28 - Resistance 84900 Omh
05 - With DWC raise temp, and measure resistance, and do a table
DWC Temp Real Temperature Resistance 28 84900 65 73 11900 120 132 2200 181 201 431 201 220 275 220 237 188
Cant raise more temp, because the thermometer only reaches 250 degrees
06 - With these info, go to Steinhart thermistor model, and put 3 temps, lower, one midrange, and higher, the web gives me B=4285, change temperature resistance, and the result its similar
07 - Put these valour in config.g M305
08 - Check if the temp its ok, and its near, but no, the new results are:
DWC Temp Real Temperature Resistance 28 84900 180 199 468 236 244 165
Whats its wrong? Maybe C parameter in M305, but wiki say thats its by default 0, and i have see in some config.g... and its near 0. How affect?
Cnnn If the sensor is a thermistor, this is the Steinhart-Hart C coefficient, default 0
Steinhart–Hart is only used if you specify C. With C=0 the beta model is used.
peirof last edited by peirof
What model its better? and how can find C?
Steinhard hard will give better results over a wider range.
go to https://configtool.reprapfirmware.org/Heaters
click on the beta value. Select custom and put in your temperatures and resistance values.
R25 : 95437 Ω
β : 6908 K
C : 3.606903e-7
put these values in config.g M305,
M305 P1 T95437 B6908 R4700 C3.606903e-7
220 _____________ 241
more temperature difference betewn measured and showed in Duet
How are you actually getting this setting to be used? Resetting the board? You can send the M305 setting direct via the console, and this should take effect immediately.
The temperatures reported don't look like they're changing much after you change the settings, ie within the variation of measurement. If you're putting these figures in config.g, do you have a config-override.g that is being called at the end of config.g, and an old setting is in that? You also didn't post what the thermistor setting originally was.
I get different results to you using the RRF configurator and the SRS Thermistor Calculator, but then they also differ from each other!
However, evidence would seem to point to you having a 100k thermistor, beta of 4285. That should be enough to use the Beta model, so send this at the gcode console and test:
M305 P1 T100000 B4285 R4700
R4700 assumes you have a Duet Wifi/Ethernet rather than Maestro.
@Veti thanks, I didn't see the previous post.
@peirof Remember you can send
M305 P1(with no other parameters) to check what the thermistors are actually set to, to confirm that any changes you make are in use. Check for config-override.g being used, and over-riding the settings you're putting in config.g.
Thanks to all,
Tomorrow try and give feedback... I al not in home