Omega Engineering RTD Configuration for LabView Use

[campel]

Hi All,

I putting together a VI that will, among other things, acquire temperature from an RTD using an NI 9217. I am using an Omega Engineering RTD with part # P-L-1/3-1/8-6-0-TS-3 RTD (which is a four wire RTD). I am not sure what options to used in the DAQ assistent to correctly measure temperature using this RTD.  

Should I use the "custom" option when specifying RTD type and then contact Omega to get the A, B, C coefficents for the Callender-Van Dusen Equation? Or is one of the preset options (e.g., Pt 3851) sufficient? What value should I used for the excitation current?

A similar question was posted here for an Omega Engineering 3-wire RTD. 

Best,

EHC

If that link I placed above doesn't work, here's the url: http://forums.ni.com/t5/LabVIEW/RTD-Configuration/m-p/769632/highlight/true#M352454

[Wayne_T]

EHC,

Only use custom if the type of RTD you have is not listed, i.e. Pt 3750 or Pt 3960.  These predefined entries are just that, predefined coefficients.  If you select custom, then you definitely need to find the A, B, and C coefficients.  All of this could probably be found in the vendor's RTD documentation, web site, etc.  Regarding excitation, again, what does the documentation specify?  The 9217 can supply 1 mA, and can be turned off if needed. 

Operating Instructions and Specifications - NI 9217

http://www.ni.com/pdf/manuals/374187c.pdf

Making an RTD or Thermistor Measurement in LabVIEW

http://www.ni.com/white-paper/14353/en/

[campel]

Thanks for your response Wayne.

Perhaps this will help someone else who has this issue:

The setting in the DAQ Assistant (e.g., Pt 3851) specifies the alpha value to be used for the RTD. Since my RTD has temperature coefficient (alpha) of 0.003581 ohm/ohm/ deg. C, then setting the DAQ Assistent to Pt 3851 is appropriate.  

Note temperature coeffiicient alpha is from Omega documentation; follows DIN/IEC 60751 standard 

The excitation current wasn't in Omega's documentation but  Omega's Tech Support indicated 1mA should be used.

[JÞB]

Since my RTD has temperature coefficient (alpha) of 0.003581 ohm/ohm/ deg. C

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I'm not going very far into my 8-Ball's capabilities when I say: "I suspect the 5 and the 8 are unintentionally transposed in that statement."

clue: Pt 3851  the 3851 refers to Alpha times 1e6

[campel]

yes

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@JÞB wrote:

Since my RTD has temperature coefficient (alpha) of 0.003581 ohm/ohm/ deg. C

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I'm not going very far into my 8-Ball's capabilities when I say: "I suspect the 5 and the 8 are unintentionally transposed in that statement."

clue: Pt 3851  the 3851 refers to Alpha times 1e6

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