Data Acquisition - RTD Sensor

[tonytiger]

Hello,

I would like to read a RTD sensor at a rate greater than 100hz which seem to be a limit on the CRIO RTD modules (9216, 9217, 9226(50hz)).  I am currently using a pxi system using an analog output and reading the voltage drop across the RTD sensor.  I would like to be able to just use a module since my current setup requires and external circuit to limit the current to the RTD. 

[Craig_]

A RTD sensor has a slow response time. This is because of the physics of the sensor, not the acquisition system.

RTD acquisition modules output data faster than RTDs can reasonably update; reading them faster than 100Hz will only reduce the accuracy of the measurements.

Try it yourself, read the temperature from an RTD continuously and put the sensor in contact with different temperatures, you'll see how slow it is to update!

[tonytiger]

I realize I maybe over sampling but I am taking other data at the same time and need it to sync up to do calculation.  The response time in still air is 0.8s for the sensor I am using and since it is not in still air but moving 100% humid air. I am assuming the response time is much less therefore should be ok to over sample a little.

[Craig_ · Accepted solution]

I'd share a start trigger, run the RTDs at their normal slow rate, and everything else at its normal fast rate. It's easy to link the data together if you know they start at the same time and how fast each task was running.

[Craig_]

You can also use the Resampling VIs to take to slow speed RTD waveforms and upscale them to the rate of the other cards if necessary.

[tonytiger]

Thanks for the input. I agree that I probably dont need to be sample that fast but I will look into the Resampling if needed.