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Lab view and relay control of a pump

Hello. I have a NI cDAQ-9174, two K type thermocouples, a NI-9213 temperature input module, and a NI-9482 relay output module. When the temperature difference of the two thermocouples becomes larger than 8 Celsius degree, a water pump should activate and keep running exactly for 5 min. When the temperature difference is again larger than 8 Celsius degree, the process repeats. How can I make them work with LabVIEW to which I am completely new?

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Message 1 of 7

Hi ab,


Welcome to LabVIEW!

To start with you should take the free lessons offered at

Then you could start with a state machine approach...

And you should define this "exactly" accuracy (and the need for exactly 5min).


Btw. a temperature difference should be noted in Kelvin. 😄

Best regards,

using LV2016/2019/2020 on Win8.1/10+cRIO
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Message 2 of 7

Im in the same boat. Did you ever make a system that worked?

My employees don't have to know I'm here.
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Message 3 of 7


Yes, I made the system work long ago. In fact, it became somewhat large and has been working without any problem since then. I attached the two snapshots of the system, one for the data acquisition block and one for the pump control block (simple text instructions are attached on the pictures). 


Basically, you first need to generate true or false Boolean signal determined by the measurement data, and then channel this signal to your pump control block to turn it on or off. Using the right "channel" is the only way to pass data from one loop to another loop while both loops are running. 


While the idea is simple, the actual implementation process may be more or less complicated depending on your teams experience. The snapshots included many other small blocks that might be helpful to you.


Good luck. 

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Message 4 of 7

Ouch!  There are some serious Rube Goldbergs in there!


The most obvious one is the way you take an array, then convert it to a cluster.  Then unbundle the cluster.  Then wire up all the individual elements to make new arrays.


You should be using Array Subset on the original array.  Almost all of your new arrays are sequential parts of the original.  You'll be eliminating more than half the nodes associated with what you are doing, and almost all of the wires!

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Message 5 of 7

Mr. Smarty Pants. You're the guy who never replied when I desperately needed help because I knew nothing about Lab View but had to finish the work in a few days. That is my only Lab View work thus far, and it'll probably be so forever. Oh, I was asked the question, which is why I replied.

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Message 6 of 7

I hope you realize that everyone on here, not counting the NI employees who have the blue bars, are volunteers.  Some of us are more active on the forums than others.  We don't always see messages to be able to reply back into them.


I have no idea what message thread you are referring to since the only other thread I see you've created on this forum is this one.

I can tell that I have never read it, and have never replied into it.





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Message 7 of 7