The Duet series supports 4 types of temperature sensor: thermistor and PT1000, thermocouple, and PT100.
Here are the pros and cons of each:
|Needs adapter board?||No||Yes||Yes||No|
|Susceptible to interference?||No||Very||Somewhat||No|
|Temperature limit||Typically 280-300C||Up to 1100C depending on type||Up to 500C depending on type||Up to 500C depending on type|
|Special considerations||Because thermistors are not very accurate, if you replace the thermistor or the electronics then the readings may change by several degC. So you may have to re-learn what temperature indications give you good prints.||To get accurate cold junction compensation, you need to run the twisted pair thermocouple leads all the way from the hot end to the adapter board. So you can't easily include the thermistor connections in a connector for a demountable hot end.||For best accuracy, use a 4-wire connection||Lower resolution than other sensors. If you use PT1000 sensors with the Duet 06 or 085 then you will probably need to calibrate the ADC by substituting fixed resistors for the PT1000 and adjusting the H and L values in the M305 command to get accurate readings. A 1K 1% resistor should give a reading of 0C +/- 2.5C and a 2K 1% resistor should read 266.5C +/- 5C.|
General recommendations ¶
- A thermistor is adequate for monitoring bed or chamber temperature
- If you have only one printer and one hot end, a thermistor is normally adequate for the hot end
- If it is important to you that multiple identical printers or multiple hot ends need the same indicated temperatures to provide identical performance, or you want to use temperatures above 280C, use PT100 sensors
- For very high temperatures, use thermocouples
- PT1000 sensors are potentially a good cost and performance compromise between thermistors and PT100 sensors. The thermistor inputs on the Duet 2 Maestro are optimised to work well with PT1000 sensors.