Reading Temperatures using PXI-4351

[lockheed_eng]

I'm having trouble configuring my PXI-4351.  I cannot get it to read a measurement from a thermocouple unless I run the NI MAX Test Panel for temperature at the same time as I run my Labview code.  If I open the test panel and set it to read a thermocouple, then my labview code will ALSO read for a thermocouple.  If I close the MAX test panel, then the labview code stops reading correctly.  it gives me erroneous readings.

Here is what I am doing in LV:

NI435X INITIALIZE

NI435X SET RANGE => high limit = 0.625, low limit = -0.625 channel = 1

NI435X SET CHANNEL MODE => Thermocouple T (8)

NI435X SET CJC => Manual mode (I do not have an accessory box connected to the 4351 - thermocouple is wired direct to the pins on channel 1 of the 4351)

NI435X SET NUMBER OF SCANS => 10

NI435X SET POWER LINE FREQUENCY => 60

NI435X SET SCAN LIST => CHANNEL 1

NI435X ACQUISITION START/STOP => START

NI435X CHECK AND READ => TIMOUT = 1000, SIZE OF SCANS = 2048

NI435X ACQUISITION START/STOP => STOP

NI435X CLOSE

I'm running LV 7.1 and MAX 4.0.0.3010, I'm not sure what my NI435X version is - and I am not sure where to find that info.

can anyone see where I might be missing something in my thermocouple setup? 

[lockheed_eng]

ok - I found the NI435X version in MAX>SOFTWARE - it's 2.5.1

[Corby_B]

Hello Reece!

Thanks for your post!

It looks like you are getting some interesting readings when when you close your test panels and just have the Lab View Program running. The first thing that I have noticed is that Version 2.5.1 is not the latest up to date version of the 435x driver. Have you been able to run test successfully in the past. One good step might be to get the updated version of the driver in case that is causing a problem. I have never run into the problem you mention before so upgrading the driver might rule out any problems with the driver installation.

The latest version is 2.5.2 and you can find this download for free here.

NI-435x 2.5.2 - Windows 2000/XP

Your program looks good from what I can tell. One thing I did notice is that you do not have a Set Temp Units.vi, so when you say "erroneous readings" does it look like its jumping to a different temperature range? Take a look at the code I am running and see how it compares to yours. Its also an example program that should be in your LabVIEW Example Finder (Help >> Find Examples).

Let me know if any of this helps and please post back if you have any questions or more concerns.

Cheers!

Corby_B

http://www.ni.com/support 

[lockheed_eng]

Hi Corby,

Thanks so much for the reply and suggestions.  I have not had this functionality working yet, this is my first developement for this application.  I tried downloading and installing 2.5.2 hoping that would fix the problem, but it did not.  the examples were not working correctly before I downloaded the 2.5.2 - it had broken links and missing VIs.  after I installed 2.5.2 the examples started working, so maybe I can figure out what the difference between my code and the examples are now.

thanks so far!

[Corby_B]

Hello Reece!

Glad to hear that your examples are now working and good luck with your application! keep me posted and post back if you have any other questions regarding this issue.

Cheers!

Corby_B

http://www.ni.com/support 

[lockheed_eng · Accepted solution]

Thanks, Corby!  I appreciate the help and I did get it working last night.  The problem seems to be in the loop.  I didn't have my read function in a loop and for some reason it's necessary even if you're only taking one reading.  I don't understand why - but at least it works this way.