Slice HT-Thermistor - RRF Preset (maybe) wrong

tom_Nbg

@dc42 oh - B in M305 isn't Beta - from the Beta-Model? Then I misunderstood it...?

dc42

Thanks. That screenshot gives the Steinhart-Hart B coefficient as 2.136058980e-4. The reciprocal of that is 4681.52. So the preset is correct.

tom_Nbg

@dc42 Thank you for clarification! I was irritated by "Beta" and don't realized that is ment as B... so everything is fine.

tom_Nbg

@dc42 - sorry - again: but the preset has other values for B and C!

Stanford: B=4681 and C=1.143895e-7

Preset: B=4723, C=1.196220e-7

When I put in the three values, THEN, RRF has the right ones!

dc42

It probably means that the RRF preset was calculated using different temperatures. Bear in mind that the Slice thermistor is rated to 500C, so it's likely that the highest temperatures used was much higher than 280C. But if you won't be going above 280C then by all means use those figures instead.

tom_Nbg

@dc42 Thank you again
My (hopefully) last question:

The configurator puts in a R4700 Paramter in M305, whereas the RRF3 configurator doesn't (in M308) - for what is that parameter used for (I don't get it from the gcode manual) - AND must it be there then in 2.05 (and not anymore in 3.0x)?

Thank you again!

droftarts

@tom_Nbg The R value is the series resistor value in the temperature sensing circuit on the Duet. On the Duet 2 Wifi, it's 4k7, on Maestro, it's 2k2. RRF3 uses the board definition to set the R value automatically, you have to put it in in M305 on RRF2.x.

Ian

tom_Nbg

@droftarts Thanks! got it!

oozeBot

@tom_Nbg so, for the layman, will you please post the final snippet of your config when you get this sorted out?

dc42

The R parameter in M305 and M308 commands is only needed in config.g files for legacy Duets, i.e. Duet 0.6 and 0.8.5 boards. For all other boards, all versions of RRF know the correct resistor values, so the R parameter is never needed.

Veti

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