PT-100 temperature constantly at 2000 degrees after failure


  • administrators

    @DjDemonD:

    Okay so it works fine and reads fine on my other machine, it must be this slightly iffy duetwifi board. I won't waste any more of your time. Thank you gentlemen. Enjoy your evenings.

    Do you have anything else connected to the SPI bus on that Duet, for example a PanelDue connected via a ribbon cable to CONN_SD ?



  • In my case the issue was with poor quality crimping on the original e3d pt100 sensor and not an iffy duetwifi board please consider that a retraction.

    I now stock pt100s without connectors with 95cm leads for less chance of a bad connection. See my signature below.


  • administrators

    @TwoTone:

    I’m having the same issue- installed new pt100 and board and it sits at 2000.
    I get 104 ohms for resistance of the PT100
    2.02 volts between 1-4 on daughter board

    2.02V is too much. Assuming you are using a 2 wire connection, you should have the 2 jumpers fitted, in which case you should measure the same voltage between terminals 2-3 on the daughter board as between 1-4.



  • @dc42:

    @TwoTone:

    I’m having the same issue- installed new pt100 and board and it sits at 2000.
    I get 104 ohms for resistance of the PT100
    2.02 volts between 1-4 on daughter board

    2.02V is too much. Assuming you are using a 2 wire connection, you should have the 2 jumpers fitted, in which case you should measure the same voltage between terminals 2-3 on the daughter board as between 1-4.

    Sorry was posting from memory.

    Actually using 4 wire and only see .0009 v across the terminals


  • administrators

    I suggest you test the daughter board, by disconnecting the PT100, connecting a 100 ohm resistor between terminals 2 and 3, and fitting the two jumpers. That should give you a reading close to 0C.



  • @dc42:

    I suggest you test the daughter board, by disconnecting the PT100, connecting a 100 ohm resistor between terminals 2 and 3, and fitting the two jumpers. That should give you a reading close to 0C.

    Sorry for the delay- took a while to get a 100 ohm resistor. I'm assuming I must have a noise issue.

    With the resistor which is around 99 actual, I get -1.4C reading

    I have 2 PT100s.

    When connecting one of them directly to the daughter board with jumpers the reading ok, about 2C higher than bed thermistor. That PT 100 reads 108 ohm.

    The other is in the hot end. When I measure resistance at the wire ends I plug into the daughter board it reads about 109 ohms.
    When I turn on the printer, it reads 2000c. Each pair is twisted and running down separate towers.

    I have the 2 wires of the PT100 going into the hotend connector, from the connector at the hotend it's 4 wires.


  • administrators

    @TwoTone:

    @dc42:

    I suggest you test the daughter board, by disconnecting the PT100, connecting a 100 ohm resistor between terminals 2 and 3, and fitting the two jumpers. That should give you a reading close to 0C.

    Sorry for the delay- took a while to get a 100 ohm resistor. I'm assuming I must have a noise issue.

    With the resistor which is around 99 actual, I get -1.4C reading

    That is about right. So it looks like the daughter board is OK. Did you test both channels?

    @TwoTone:

    I have 2 PT100s.

    When connecting one of them directly to the daughter board with jumpers the reading ok, about 2C higher than bed thermistor. That PT 100 reads 108 ohm.

    The other is in the hot end. When I measure resistance at the wire ends I plug into the daughter board it reads about 109 ohms.
    When I turn on the printer, it reads 2000c. Each pair is twisted and running down separate towers.

    I have the 2 wires of the PT100 going into the hotend connector, from the connector at the hotend it's 4 wires.

    If they are twisted pairs then it is unlikely that they are picking up interference. Please check with your multimeter whether you can measure any resistance between the PT100 wires and the case of the PT100 sensor. It should read out-of-range even on your multimeter's highest resistance scale.



  • Hi,

    I thought i share my experience with PT100 and my Printer setup. I got random 2000 degree spikes throughout the print. It turned out to be noise from the Layer Fan which wires go thru the same cable as the PT100. Reducing the Layer Fan PWM frequency to 10Hz solved the issue and the fan still works very well.



  • Between work and my son's busy schedule we're finally getting back to this, where do I adjust the fan's frequency?



  • @twotone by modifying the M106 fan command in config.g for the particular fan you want to change. Frequency is controlled by the F parameter.

    https://duet3d.dozuki.com/Wiki/Gcode#Section_M106_Fan_On



  • @phaedrux Thanks



  • Just thought I would post to wrap up my problem and incase anyone else runs into the same issue.

    I was using a Makerhive Yellow Jacket Quick Clip.
    It seems like the gauge of the PT100 wires was too small. It made just enough contact for the resistance measurements, but failed when powered up.

    When I routed the PT100 using a seperate JST plug, it all works correctly now.


 

Looks like your connection to Duet3D was lost, please wait while we try to reconnect.