Precision Piezo PT1000 sensor?

[Samuel_k]

Hi all,
I bought a couple of Precision Piezo PT1000 sensors that I'm planning to use together with a Maestro, but the temperatures are off by quite a bit. I taped down a trusted E3D thermistor to the heat block to check the readings, and even though they give the same reading at room temp, the PT1000 thinks that 100°C is at 83°. The PT1000 is configured using M305 P1 X501.

I've found lots of other threads about PT1000 issues with various other sensor suppliers, but not this one, and since it seems to be quite common among Duet users I wonder if there's something off with my sensors. How does everyone else configure them? Is it a lost cause to get them working on an ADC channel, and should I just bite the bullet and tune them in as thermistors instead? (ping @DjDemonD )

[Moriquendi]

You need to specify the value of the series resistor in order to get accurate readings

M305 P1 X501 R4700 ; Specifies a 4.7k resistor for the Duet Wifi

M305 P1 X501 R2200 ; Specifies a 2.2k resistor for the Duet Maestro

Idris

[dc42]

@moriquendi said in Precision Piezo PT1000 sensor?:

You need to specify the value of the series resistor in order to get accurate readings

M305 P1 X501 R4700 ; Specifies a 4.7k resistor for the Duet Wifi

M305 P1 X501 R2200 ; Specifies a 2.2k resistor for the Duet Maestro

Idris

That shouldn't be necessary, because the default values are correct for all Duets except the Duet 085 and some Duet 06.

[Moriquendi]

Is that a recent firmware feature?

Idris

[dc42]

@moriquendi said in Precision Piezo PT1000 sensor?:

Is that a recent firmware feature?

Idris

RepRapFirmware for the Duet WiFi, Ethernet and Maestro have always had the correct default values. The Duet 06/085 has the default set to 1K because the Duet 06 originally used 1K resistors, but that was changed to 4.7K in later Duet 06 boards and in the Duet 085.