Reading in a thermocouple with usb-6009

[C0ld]

Hello,

I am am trying to write a labVIEW program that will display data readings from various sources, the first being a Type K thermocouple. My problem is really that I only have a usb-6009 on hand. Having taking only one semester of LabVIEW (Data Acqauisitions), I am in a bit over my head.

I have my thermocouple connected to the 5th and 6th anolog channels of the 6009. I've also inserted a 10kOhm resistor in line with the thermocouple as directed by NI. My reading is a constant 0.

Note: I realize that once I get my program is written correctly I will need to amplify the thermocouple's signal in some way.

Any help would be greatly appreciated. Attached is my current VI (ignore the gibberesh that does not relate the the Temperature). 

[apok]

first of all...you have infinite loops (false wired to your stop, which means you have to hit abort upon exit) and no way of shutting down both without it. second, usb 600x will not do you good on the thermocoupling aspects.

[C0ld]

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@apok wrote:

first of all...you have infinite loops (false wired to your stop, which means you have to hit abort upon exit) and no way of shutting down both without it. second, usb 600x will not do you good on the thermocoupling aspects.

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I understand your first point, but fail to understand why this is a negative, or what your solution is (just add control stops for both loops?). And, to your second point, if I amplify the signal coming from the thermocouple, then a 6009 should do just fine...should it not?

[Dennis_Knutson]

Well, you can only use a single loop with a single 6009 so you will only have one stop button. It is always better to do a graceful stop and clean up.

You don't have any error indicators wired up. I'm sure you are getting a resource reserved error because you can only have a single task. I also don't understand what you mean by 5th and 6th channel. Are you configuring as differential or single ended?

[C0ld]

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@Dennis_Knutson wrote:

Well, you can only use a single loop with a single 6009 so you will only have one stop button. It is always better to do a graceful stop and clean up.

You don't have any error indicators wired up. I'm sure you are getting a resource reserved error because you can only have a single task. I also don't understand what you mean by 5th and 6th channel. Are you configuring as differential or single ended?

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So, always better to have a control stop. Easy enough. 

"I'm sure you are getting a resource reserved error because you can only have a single task." Could you elaborate?

I'm attempting to configure as differential. From what I understand, differential is the appropriate way to read in a thermocouple.

Also, thanks for the replys thus far.

[Dennis_Knutson]

It's a common error for beginners. You simply must use a single task for a common hardware resource. In other words, all analog inputs have to be in a single task. You use multiple DAQmx Create Channels with the single task.

For differential, you have to pay attention to how the driver pairs channels. If you use AI0, then it automatically pairs that with AI4. AI1 is paired with AI5, etc. If your wiring does not match your input selection, you will read garbage.

[C0ld]

I will try to make use of all this info when I get back in the lab, I'm sure I will have more questions.

[C0ld]

I am attempting to use http://zone.ni.com/devzone/cda/epd/p/id/4996 in order to better understand how to build my own vi. I'd like to see my thermocouple read in some value in this vi first.

However, I'm having problems specifying my physical channel. The front panel "physical channel" drop down menu only displays "Browse". There is nothing in the browse window and there is no option to create/specify a physical channel.

What am I missing?

[RavensFan]

Do you see your DAQ device in Measurement and Automation Explorer?  You need to be able to see it there first before you can see it in LabVIEW.

[C0ld]

ty RavensFan. My 6009 was not being detected at all ...something as simple as that.  The vi is now reading data in at least. Now to figure out why it's highly unstable.