Problem with Pt100



  • hello I'm having problems with the pt100 sensor. if I connect the sensor directly to the MAX31865-based daughter boards I have no problems and I can have the right temperature the problem is when the wires are firmly in order to arrive with the sensor to the cartridge, it no longer detects the temperature and marks 2000 degrees. how can I fix it? do I need a special cable? thanks



  • I solved. the cable was too double. sorry for the post as it is eliminated?



  • FYI I recently had a problem with intermittent connection on an e3d pt100 and it was one of the blue braided leads from the sensor poorly crimped into the pre-attached connector. I cut the connector off and soldered it to the longer leads (shielded) I am using which run back to the duet.



  • what are the shielded cables you used? because the temperature is not constant but varies eg between 189 and 194 when imposed 190 degrees. will it be because the cables are not shielded?



  • @Dracula36:

    what are the shielded cables you used? because the temperature is not constant but varies eg between 189 and 194 when imposed 190 degrees. will it be because the cables are not shielded?

    Have you run the autotune system on the heater this is more likely the cause but I use a twisted pairs Cat 5 cable but it carries more than just the PT100 if you do use cat5 then it must be stranded and not solid core



  • I did the autotune but I did not solve the problem … I also narrowed the thread thinking it was the problem. if I connect the pt100 directly to the board I do not have this problem ...



  • ok in that case make sure you use Twisted pair cable and connect it in 4Wire mode



  • I am using pt100 on my corexy and used canbus 2-core shielded cable (ground the shield to a GND pin on duet). But this was because I thought the intermittent 2000 degrees I was getting was interference, it wasn't it was an intermittent connection, so maybe the shielded cable is unnecessary.



  • I use 2 twisted pairs of a 8-pairs shielded cable in a 4-wire connection. No issues whatsoever. Cable is around 100cm long.


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