If I have a bunch of thermocouples reading some low temperatures and a bunch reading higher temperatures, how can I get Labview to figure out the transition zone between them?, i.e. which thermocouples make up that transition zone??

[jon_mcbee]

It is good to have a descriptive message subject line, but it is best to included the question in the body of the post.  As for your question, how are the thermocouples laid out physically?  From what you said I am picturing an array of evenly spaced thermocouples in a line all being read in by LabVIEW and you want LabVIEW to take these readings, as well as have input as to the physical locations of the thermocouples and from this information tell you where the transition zone occurs (you will also have to define the transition zone).  Am I on the right track here?  What have you done so far?

[GenU1Chevy]

Hi Jcmbee,

Yes you hit it right on the nose.  We have a bunch of thermocouples all in align and we want to measure where that transition happens from the last cold temperature to the first high temperature and then find which thermocouples are inbetween those values.  Once we find those thermocouple we will then take the midpoint to define the length we are looking for.    As of now we don't have something like this written.  I'm new to this LV stuff.  If you have any ideas I'm all ears!!!  Thanks!!

[jon_mcbee]

What hardware are you using to read in your thermocouples?  Is it the NI USB9211?  Is it third party?  Once you are reading the thermocouples with LabVIEW the task of finding the transition should be pretty straightforward.

[GenU1Chevy]

We are serially using an Agilent 34970A to record the thermocouple values.

Thanks,

Jeff K.

[jon_mcbee]

Try this link to download drivers for that module.  You may also find this link helpful.  There may be other drivers out there if you find that these don't suffice.  Have a look and let me know what you think.  Like I said, this is the hard part 😉

Message Edited by jmcbee on 12-09-2008 12:53 PM

[GenU1Chevy]

Thanks for the links however I've already downloaded the drivers for the 34970A and I've have had luck using them in the code.  I can record the data and everything but I now I need to help to figure out how to measure that transition zone when measuring all those thermocouples??? 

[jon_mcbee]

Can you please post the code you are using to read in the thermocouples?  Are you using one of the driver examples?

[GenU1Chevy]

Here is what I'm working with.  You might get a few errors due to missing subvi's.

[jon_mcbee]

It may be useful for you to look into using a state machine architecture for this program (assuming you ever get the inclination to rewrite it).  As for your question, from what I can tell by looking at your block diagram you are using the "HP34970A EZ Temperature.vi" to read the actual thermocouples in from the GPIB.  That vi is missin but it looks like you are supplying an address for the thermocouples with the string control?  The output is the array of voltages that you build into a 2D array, add an offset to and then pass to the "Swales temp splitter.vi", which outputs arrays of 10 temperature readings?  Is this right?

How do you want to define the trasition zone?  What is hot and what is cold and what is considered to be tranisitioning from hot to cold?  What do you expect the temperature profile to look like?

Message Edited by jmcbee on 12-09-2008 02:03 PM