fpga thermcouple

[Gotti_uncc]

I need to create a thermocouple VI I created one in the labview with daqmx's but now my group has decied to now use a myRio. Which uses FPGA so the daqmx code will not work. I have been working with it for a minute now I figured it was time to ask some people that are more experienced with this I will attach my daqmx code an hopefully someone will help me make the conversion. Or lead me a direction to do, my issue is it does not have like a palette for the analog input themperature for the thermocouple sampling clock. If anyone could help this would be great I am working on a senior design project an this has me stuck.

[GerdW]

Hi Gotti,

when you're directed to use a new hardware why don't you read it's manual? And why don't you just take the information available at NI's website?

You can forget about all that DAQmx. Either use the ScanEngine from the RealTime host side or do your work in the FPGA with direct access to the analog input module. Anyway: RTFM! Look at the examples provided by NI!

www.NI.com/myrio is the place to go...

[Gotti_uncc]

I did look at the website and I did read the manual. I know that you can not use daqmx code. I did not find any examples for a thermocouple for myRio but I did find one for compactRio. But the problem with that is it has i/o modules for the thermcouple but the myRio doesn't so that's when I got confused an decided to see if anyone could help....

[GerdW]

Ho Gotti,

I found this on the myRIO website. Video 3 shows how to program FPGA I/O.

Even when it says cRIO you can do the same on myRIO. You just use a different I/O node...

[Gotti_uncc]

I will try this out, when I talked to technical support they told me the modules on compact wouldn't work for the Rio. I appreciate your help though I will give it a try!

[srm@viewpointusa.com]

to give you a more helpfull answer, the myRIO is not well suited to measureing a thermocouple directly.  that is probably the reason you have not found examples for it.

in order to measure a thermocouple, you need a couple of things.

cold junction reference.  knowlege of the temperature of the connection of the thermocouple is integral to the solution.  if you do not have a cold junction reference, you must assume the CJR temperatue or place a reference junction in ice water to compensate for the CJR.

an accurate low level voltage input.  the voltage generated by a thermocouple is very low.  typically in the millivolt or 10s of millivolt range.  the myRIO only has a low resolution high voltage range input.  neither are good for TC measurement.

so unless you plan to condition the signal before using the myRIO, you will not be happy with the result.

[Gotti_uncc]

Stu,

Thank you for this reply. I was having serious issues with this now it all makes sense.