ESP8266 Community Forum

- Sat Oct 27, 2018 7:28 am #78904

I have not used the MAX31865.

Mostly I have used J or K thermocouples with a different Maxim chips, never RTD. Also SPI interface. One application I needed eight thermocouples so I used a 3-8 decoder to give me more chip enables.

I have never needed to measure very cold temperatures, only high.

This is the problem with SPI.
Need more entries.

I always need to read very low temperatures that go up to -200C normally.
It's difficult, but sometimes I need to read high temperatures as well.
The more precise and cheaper the better.
Still do not know what the best solution, thermocouples or PT100. Both are very similar.

Which do you prefer?

- Sat Oct 27, 2018 12:06 pm #78907 Measuring Temperature From PT100 Using Arduino :-

https://www.instructables.com/id/Reading-Temperature-From-PT100-Using-Arduino/

Food for thought?

- Sat Oct 27, 2018 2:38 pm #78908 I can't say what is best for you. I prefer thermocouples as that is what I am familiar with. The processes that i have dealt with had thermocouples originally so I stuck with it. Thermocouples need to be connected with thermocouple wire of the same type. The resistance of the wire connecting the RTDs is a factor that needs to be considered. With thermocouples resistance is not significant.

In the end the choice is always a consideration of many factors.

If you are considering thermocouples then look at MAX31856. It would be my first choice in a new design.
https://www.adafruit.com/product/3263

https://www.aliexpress.com/item/MAX3185 ... 82894.html

- Sat Oct 27, 2018 3:02 pm #78910

Measuring Temperature From PT100 Using Arduino :-

https://www.instructables.com/id/Reading-Temperature-From-PT100-Using-Arduino/

Food for thought?

It seems is only for two wire pt100.