9211 Temperature Measure with RTD

[Kirika]

HI all

I only have a comapctDAQ and want to measure temperature with RTD. I know 9217 is suitable for

RTD measurement, but it's only for cRIO. I checked "example finder" in labview and found a "Acq RTD sample.vi",

and 9211 is in the requirement list. It seems that 9211 can measure RTD output. But obviously I can't

directly connect a RTD into 9211.

So far I know I have to do something before I connect RTD to 9211

    1.build a resister bridge and excitation power

    2.connect the bridge output Vb into 9211

Could somebody tell me how to setting the DAQmx task in MAX or Labview or something

I forget? Or do you have any suggestions if 9211 doesn't work with RTD?

Thanks

Ryan  

[Broken_Arrow]

You're on the right track regarding the resistor bridge. I don't think MAX or LabVIEW is going to get you to a simple "plug-n-play" answer, because your hardware does not have the inner electronics set up for direct connection of a RTD (but you already know this).

All you need is a resistor bridge (made from discrete resistors), and an opamp to convert current to voltage. Less than $1 worth of parts and an hour or so of work. Look on the internet for RTD circuits.

You hardware supports an AI of -80..80 mV, so you'll have to do some scaling before the input with another opamp or a resistor divider. Once connected, setup the scale in LabVIEW to two known temperatures. I use a slushy ice mixture for 32 F and room temperature for the other "extereme".

Have Fun

Message Edited by Broken Arrow on 02-02-2007 08:49 AM

[Kirika]

Hi Richard

Thank you for your help. I know what to do next!

Regards,

Ryan