6210 - thermistor

[calaf85]

hi,

I want to connect an NTC (100komh) to my 6210.

When I start the readings, it seems NTC doesn't work: the temperature is always 0 Kelvin!!

instead, if I try to read the input signal as a voltage, it seems to be ok.

where am I making a mistake?

I'm using this connection diagram.

furthermore these are the Vex thermistor settings.

[AndreaN]

Hello Calaf85,

are you sure that you need to supply an external voltage instead of a current? Try to create a DAQmx Task for RTD, you can choose a custom one and set the coefficients value. Maybe your NTC requires a current and that's why you don't read anything out of it with the current setup.

Have a nice day.

Andrea

[calaf85]

hello andrea,

thanks for the answer.

I tried to create a task for RTD: I remember that the temperature was different from 0Kelvin, but its value was always absurd and, above all, oddly fixed.

currently, I'm working with RSE voltage channel and applying a custom scale to transform voltage into temperature.

[AndreaN]

Ciao Calaf85,

you're saying that now you just use a Voltage task and then use a custom scale. So in this way I guess you'r not exciting the thermistor or are you using the Custom Voltage with Excitation task?

If you just use the Voltage task and then by converting the data into temperature you get the correct results it means that your thermisotr doesn't have to be excited, so that's why you couldn't measure correctly with the previous tasks.

You could also try the RTD channel choosing None as Iex Source and Custom ad RTD Type

Ciao,

Andrea

[calaf85]

ciao andrea,

at the moment I'm working with a RSE voltage channel, but with the same connection diagram above (Vex is 12,2V, R1 is 78 kohm and NTC is 100kohm at 25°C).

I created a custom scale (based on NTC specifications and the characteristics of my circuit) to transform the output voltage in temperature.