MAX31865 RTD Low Threshold

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ajokela
 
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Joined: Mon Dec 13, 2021 8:55 pm

MAX31865 RTD Low Threshold

Post by ajokela »

Order #2733556-3471611041

I have purchased several MAX31865 and several different RTD PT100 sensors. All the sensors are three wire. I have checked the resistance of the wires, the matching pair is ~2 while the other single to the pair is ~109 ohms.

I am using the default MAX31865 sketch. The only time I made a change was when I tried using only two of the three wires on a probe. I still had the same result.

Adafruit MAX31865 PT100 Sensor Test!
RTD value: 0
Ratio = 0.00000000
Resistance = 0.00000000
Temperature = -242.02
Fault 0x40
RTD Low Threshold

I have been following this howto: https://learn.adafruit.com/adafruit-max ... -amplifier

I also have read through: viewtopic.php?f=31&t=166096

Attached are photos of my setup. If/When there needs to be a different angle for a photo, please ask.

Thanks,
-AJ
Attachments
sparkfun-uno.jpeg
sparkfun-uno.jpeg (487.49 KiB) Viewed 610 times
Three wire
Three wire
threewire.jpeg (333.81 KiB) Viewed 610 times
Three wire
Three wire
threewire-1.jpeg (421.1 KiB) Viewed 610 times

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adafruit_support_bill
 
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Re: MAX31865 RTD Low Threshold

Post by adafruit_support_bill »

The connections look good. Make sure that you have cut fully through the bridge on the "24" side of the ""24 - 3" jumper. It is hard to see in the photo.

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ajokela
 
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Re: MAX31865 RTD Low Threshold

Post by ajokela »

Here are close up photos of the cut jumper.

I am not seeing any difference in the output. Still the RTD Low Threshold
Attachments
signal-2021-12-14-200849.jpeg
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signal-2021-12-14-200907_001.jpeg (288.63 KiB) Viewed 604 times

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adafruit_support_bill
 
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Re: MAX31865 RTD Low Threshold

Post by adafruit_support_bill »

We can try replacing the board. Please contact [email protected] with a link to this thread.

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