Cannot change current excitation on NI 9219 - alternative?

[Kjerland]

Hi

We have a NI 9219 module and we're trying to measure a temperature sensor.

Up until around 268*C it works perfect, but at that time the temperature starts to decrease even though it should continue to rise!

After I revisited the datasheet, I saw on page 6 that with an excitation of 0,5mA the sensor will decrease its value when it goes above 270.

Even though this is correct, it won't work for our application, so I tried to change the excitation current, but this just gives me an error.

Does it excist another module that I can use instead of the 9219 so that I can change the excitation current to 1 or 2 mA, or is it simply not possible to do this measurement with NI equipment?

Any help would be greatly appriciated here!

Best regards

Trond

[AJost · Accepted solution]

Hi Trond

The 9219  module gives a constant voltage excitation and I just estimated that it would result of a current <0.9mA for your sensor, which is also the maximum the 9219 can deliver.

The easiest solution would be to use a current output module like the 9265 to deliver the current to your sensor and still use the 9219 to read the voltage drop across the sensor.

Andreas Jost

Applications Engineer

National Instruments