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Error -200478 - Specified operation cannot be performed when there are no channels in the task

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I am writing a task in NiDaqmx to read 8 thermocouples from 2 NI 9222 and 4 thermocouples from a NI 9223 modules. Under CJC Source I have entered channel and specified a K-type thermocouple connected to a NI 9219. All modules are located in the same cDAQ9178 chassis.

 

 

 

I get the above error.

 

I add the CJC channel and it complains that I have duplicate readings of the same channel in the one task.

 

The environment where this will be installed will vary greatly thus setting the CJC to Constant is not a viable option.

 

Any help would be appreciated.

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Here are some screenshots that may aid in the understanding of what I have configured

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Greetings,

 

Is there any specific reason why you are using NI 9222 and NI 9223 modules to read your thermocouples?

If you have the option to use a NI 9213 (http://sine.ni.com/nips/cds/view/p/lang/sl/nid/208788) module instead, it would be much easier (and cheaper).

The NI 9213 module can read 16 thermocouples at the same time and also has a built in CJC source, thus you would only use one module instead of four.

 

That being said I tried your configuration with simulated hardware in MAX and the task did run, but I didn't get any values out of it. I don't know if this is because of simulated hardware or there is another reason.

Unfortunately I don't have the 9222 and 9223 modules to test it with real hardware.

Attached is the VI I used (LV2010).

 

Best regards

Matej

/* A smart device is only as smart (stupid) as its programmer. */
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I think the problem is that you put the NI9219 channel on the bottom of the list.

Try putting it on top so you read that channel first. I did the same in my VI.

 

Matej

/* A smart device is only as smart (stupid) as its programmer. */
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Solution
Accepted by topic author Le_Gross_Bill

Simple reason - we already own the NI 9222s and the NI 9223. I'll check the NI9213 prices and see if the group has the budget.

 

I looked at your program and compared it to mine. Tried to select the CJC channel as Temperature_12 but all local channels were greyed out. BUT I moved Temperature_12 up the order to the top as you had and Voila! it's available to be selected. I set all the 9222s and 9223 channels to to point to Temperature_12 and it saved without error.

 

So I'd say that putting the CJC channel as the first channel to read fixes the problem - this makes sense as the subsequent channels need a reading to use as their CJC. Where that logic breaks down is when you consider that the 9222 and 9223 channels are simultaneous channels but that is a topic for another post!

 

For now, thank you very much for your assistance.

 

Best regards,

 

Dean

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Glad I could help.

Don't forget to mark your post as solved.

 

Best regards

Matej

/* A smart device is only as smart (stupid) as its programmer. */
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