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hysteresis (bang-bang) control for thermostat in cDAQ

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I want to implement a closed-loop ON/OFF control with bang-bang (hysteresis) control, such as room temperature. The loop could use NI9219 (cDAQ) device to measure the feedback temperature signal of the room and use NI9401 (cDAQ) device as a digital output (DO) control. The control output turns the heating unit ON if the room is too cold(17 degrees) or OFF if the room is too warm(23 degrees). The hysteresis determines at what point the heating unit turns ON or OFF. For instance, if the hysteresis is set to 5, and the set temperature to 21 degrees, the heating unit turns ON at 17 degrees and OFF at 23 degrees.

 

A example is found as follows 

http://zone.ni.com/devzone/cda/epd/p/id/505 

Do I need to have LabVIEW PID and Fuzzy Logic Control Toolkit and is it coming free with the Labview2009 licence? Can I do this without this toolkit?

All help is appreciated.

Regards

Bing

 

 

 

 

 

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Message 1 of 18
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here is one way

2pointcontrol+hyst.png

the loop just store the heater status ... no big deal.

the symsee attachement gives a curve like this: 2pointgraph.png

 

I'm shure it can be solved even more simple, however I go for my first coffee now.....

 

 

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'


Message 2 of 18
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Thank you fror your quick reply Henrik.

 

I need a 2 set values THIGH and TLOW. The hysteresis area is between these 2 boundaries.

For example

40degreeC, heater OFF untill termperature drop to 20degreeC

20degreeC, heater ON   untill temperature rise to 40 degreeC

Any ideas? Thank you.

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Message 3 of 18
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Set temp=30 , Hyst=10 will do the job, however, why you should be able to find out by yourself 😉

 

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'


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Message 4 of 18
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Solution
Accepted by topic author NCLbingji

Here is the frontpanel of the 'new type' of 2 point control. The code is even simpler (select and less?)  , however no more homework assistance until you post your code 😉

2pointsym.png

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'


Message 5 of 18
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Thanks Henrik.

That is a very clever way to do. I do need to work on the programming with Labview, which I think is quite different from C programing.

What is the best point to start please?

I have read the book <<Labview for Everyone>> and tried some demo VIs from the forum.

 

Regards

Bing

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Message 6 of 18
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Hi Bing,

 

I have a number of suggestions for you in terms of successfully getting up and running with LabVIEW. Firstly and foremostly I can not emphasise enough how great the LabVIEW Customer Education courses that we offer at NI UK are. The LabVIEW Core 1 and Core 2 courses provide a fantastic grounding in LV programming. These courses are also available in a self-paced format whereby all of the course material is sent to you for you to work through at your own pace. For more information on such courses, refer to the following ink.

 

NI Training and Certification

 

The other option if you have an active support contract with NI is that there is a whole host of On Demand training material available at the Service Resource Centre. I have linked this below for you convenience.

 

Service Resource Center

 

If neither of the above suggestions are an option, then I would recommend the Getting Started with LabVIEW guide which I have also linked below for you.

 

Getting Started with LabVIEW

 

I hope this helps.

 

Best Regards,

 

Christian Hartshorne

NIUK

 

 

 

Message 7 of 18
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Hi,

 

May I have your new code?

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Message 8 of 18
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Hey,

 

I would be also interested.

Thanks in advance!

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Message 9 of 18
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Sorry, as already noted:
No more homework assistance until you post your code
Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'


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Message 10 of 18
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