Temperature control by a digital output

[jas1991]

Hello all,

I want to implement a temperature control based upon temperature measurements from a heated vessel. I am using a heating tape (288 W) in order to heat up some water in a vessel. Since we want to establish a temperature setpoint of 92 C I was wondering how could I implement that to LabVIEW. The main function of the .vi program should drive the digital output relay to either turn on or off as a result of obtaining a higher/lower temperature of 92 C. The components I am using for that are the following:

- DAQ : NI USB-6009

- Thermocouple Type K

- Heating tape (288 W)

- SSR (240 VAC,25 A)

I have found the following .vi configuration program however I do not understand how to set up your own data input, for instance to set the port of the DAQ you will be obtaining data from.

Thank you very much

Regards

Joan

[apok]

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@jas1991 wrote:

Hello all,

I want to implement a temperature control based upon temperature measurements from a heated vessel. I am using a heating tape (288 W) in order to heat up some water in a vessel. Since we want to establish a temperature setpoint of 92 C I was wondering how could I implement that to LabVIEW. The main function of the .vi program should drive the digital output relay to either turn on or off as a result of obtaining a higher/lower temperature of 92 C. The components I am using for that are the following:

- DAQ : NI USB-6009

- Thermocouple Type K

- Heating tape (288 W)

- SSR (240 VAC,25 A)

I have found the following .vi configuration program however I do not understand how to set up your own data input, for instance to set the port of the DAQ you will be obtaining data from.

Thank you very much

Regards

Joan

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you are going to have some limitations with thermocoupling to a 6009, unless you use an amplifier. you are currently writing an analog output, i would use the digital ouput to your ssr. your code will work, but change your wait ms to 100 and not 10000 and the user interface will work that much quicker. there are plenty of example vi's prepackaged with your labview version under 'help'>> 'find example'>>'hardware input and output'....there you will find analog input thermocouple and digital output single line output to the ssr

[jas1991]

Thanks apok for your response.

Yes I agree with you, so we are going to use a signal conditioner but since we don't have it just a thermocouple will be sufficient.

My main problem is how to wire all the components since I have the feeling that something might be missing in there, and before proceeding with the LabVIEW connection I just wanted to make sure the wiring is fine so if you could provide me that help I would be grateful.

The issue with the LabVIEW implementation is not setting the whole thing up (as you say that part is really straightforward since most of it can be found in the example folders) but to tell the software that the DAQ will have some connections at certains ports. For instance by inserting a DAQ Assistant that can be made, however in the code I posted that is not done so I don't know how to set that precise part.

Thanks

[camerond]

If you wouldn't need to sample the temperature more than once a second (thermal inertia in your system might be greater than that), why not just get an inexpensive Omega (or other manufacturer) temperature controller and control it from the PC serially? I haven't looked into it, but there may well be some which update their output at faster rates, too. That way you won't have to construct your own T->V calibration curves.

Cameron

[apok]

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@jas1991 wrote:

Thanks apok for your response.

...but to tell the software that the DAQ will have some connections at certains ports....

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you can assign the output/input's through the channel settings, whether it's a whole port (8/16/32 lines) or a single line on a different port. btw, i hate using the express vi's...

[jas1991]

Thanks apok, I finally solved it. However I am still struggling with my power supply and relay connection.

I am attaching a picture of both, as a power supply we are using a wall socket as you will see.

Thanks!

[AnalogKid2DigitalMan]

Manufacturers and P/N's of your SSR and tape would be of help here.

I also did not see a black (line, or 'hot') wire on your 120VAC cord.

If you are unfamiliar with wiring up such components, it may be better to find someone at your location to assist, lest the sparks may fly and you will let the magic smoke out. Wear safety glasses too for initial hookup and test.

We can still try to assist, though.

-AK2DM

[jas1991]

Dear AK2DM the cord has a black,green and white wires, the problem is that I don't know exactly how to connect them properly to the USB-6009.

The SSR is a prx ks224510

Thanks

[apok]

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@jas1991 wrote:

Dear AK2DM the cord has a black,green and white wires, the problem is that I don't know exactly how to connect them properly to the USB-6009.

The SSR is a prx ks224510

Thanks

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ooooooooooouuuuuuuuuuuuuuuuuch! PLEASE DON'T DO THAT!!!!!!

have a qualified electrical engineer do this..Obviously you have not read the 6009 specifications on voltage?

note: is this a home or hobby project? from your picture, it looks like your black wire is connected to your green wire?

[jas1991]

This is a student project and I am the one responsible for doing that, besides I don't think that should be too difficult to connect once you know how to do it!