PT100 without PT100 board on Maestro

[A Former User]

This is mostly for curiosity, but I've seen claims its possible to read off PT100 sensors by fudging the thermistor coefficients, or by pretending its a PT1000 sensor and fudging the given seriers resistance value.

@dc42 said in Controlling a Cetus3D with Duet3D 0.8.5:

@fotomas said in Controlling a Cetus3D with Duet3D 0.8.5:

@cookie

I'm using the original cetus thermistor. It works well after finding the correct values for it.

I do not think a negative B value is common.
M305 P1 R4700 T112 B-425 C7.060000e-8

Looks like you are using a PT100 but you have connected it directly to the thermistor input. This will give you a very poor resolution and you should use the PT100 daughter board instead. However, if you want to use a direct connection then I suggest this:

M305 P1 X501 R47000

This says you are using a PT1000 sensor, but inflates the series resistor value by a factor of 10 to compensate for the fact that you are actually using a PT100.

Adapting to Duet Maestro board I try to add a virtual ambient temp sensor:

M305 P103 S"ambientX502" X502 R22000 ;doesnt work works wiht P103
M305 P103 S"ambientX2" X2 R2200 T105 B-425 C7.060000E-8 ; doesnt work works wiht P103

but if I map E1 thermistor to E0 it does work:

M305 P1 X502 R22000 ;works
M305 P1 X2 R2200 T105 B-425 C7.060000E-8 ;works

edit: figured it out.