PT1000 cable length, connector, and wire type

[briangilbert]

@MSquared I think thats more for PT100 sensors..

[MSquared]

@briangilbert Touche'. Well in that case I probably can't tell you anything you don't already know. If it were me I would probably just use one of the twisted pairs I have lying around from the dismantling of an ethernet cable. The resistance of copper wire at the length we would be talking about would be negligible, it won't be carrying any meaningful current and while not strictly required the twist would give it a little extra protection from interference.

[DjDemonD]

I havent tried yet putting a few joins in a pt1000 wire to see what effect it has. Be quite worth trying though. Ours come with 2m cables.

[dc42]

For a PT100 sensor, 1 ohm of resistance in the cable and connectors will increase the temperature reading by 2.5C. For a PT1000 it would be 0.25C. So cables and connectors won't have much effect with a PT1000.

[briangilbert]

@dc42 thanks, I was hoping this would be the case.

[c310]

@dc42 how do we config DuetWiFi for PT1000 than? there is nothing in WiKi, just pt100... thanks!

[DjDemonD]

Although it is not necessarily "proper" if you find there is an offset in the temperature, or as I do prefer to offset the temp reading to show the bed surface temperature then change the series resistor value by a small amount from the console, then update config.g.

I have got 3 connected to my cylinder delta using the following config

M305 P0 X500 R4700  			; heater 0 uses a PT1000 connected to thermistor channel 0 which has a 4.7K series resistor
M305 P1 X501 R4700  			; heater 1 uses a PT1000 connected to thermistor channel 1 which has a 4.7K series resistor
M305 P2 X502 R4700  			; heater 2 uses a PT1000 connected to thermistor channel 2 which has a 4.7K series resistor

[c310]

@djdemond said in PT1000 cable length, connector, and wire type:

3 connected to my delta cylinder....
connected to thermistor channel 0.... channel 1 .... channel 2

does it mean you have simmultanius 3 readings from the same head AND you have 2 PT100 boards?

[DjDemonD]

No I have 3 PT1000 sensors. One for Bed, one for hotend and one for chamber. No daughterboards at all. PT1000 can be connected directly. See my sig.

[dc42]

@c310 said in PT1000 cable length, connector, and wire type:

@dc42 how do we config DuetWiFi for PT1000 than? there is nothing in WiKi, just pt100... thanks!

Yes there is, https://duet3d.dozuki.com/Wiki/Connecting_thermistors_or_PT1000_temperature_sensors.

[c310]

i missed it. thanks!

Use the M305 command as for a thermistor, but add parameter X500+n where N is the channel number. Only the R, H and L parameters are significant. Example:

M305 P1 X501 R4700 ; heater 1 uses a PT1000 connected to thermistor channel 1 which has a 4.7K series resistor