PID temperature controller with on/off and lm35 sensor

[PaddyD]

Hi All,

I am currently trying to finish a temperature controlled box for a collage project, I am trying to control it with PID but I am not having much luck. Would anyone have any advise on the attached vi on where I am going wrong. Any help would be greatly appreciated.  

[GerdW]

Hi Paddy,

I am not having much luck.

How much luck do you have?

What is the exact problem?

Why do you need a PID for a simple ON/OFF controller?

(Mind to attach a downconverted version of your VI?)

[PaddyD]

Hi GerdW

Sorry I am quite new to labview and PID, i am trying to keep a constant temperature in the box using Arduino with both a fan and a heater, but im not sure how to implement PID to deal with sudden changes in temperature.

Regards

Paddy

[GreennRed]

Hi Paddy,

If you're still a bit stuck go to Labview home screen. Click on Help > Find Examples. Click on Temperature tab, scroll down and click on temperature. Click on and open On/Off controller VI. This or some other VIs there might give you some ideas. But don't be too bothered if your VI doesn't run. Get a load of snips of VIs, error codes and get cracking on a report. Even if it doesn't work you'll get decent marks for your objectives, plan,method, issues, any learnings and how you go about troubleshooting them. Spending much more time at this stage might affect your exams. 

Best of luck.

[GerdW]

Hi Paddy,

now I had a chance to have a peek into your VI…

Sorry I am quite new to labview and PID

As you are new to LabVIEW you should take the Training resources offered in the header section of the LabVIEW board1

When you are new to PID control too you should read a book about that…

i am trying to keep a constant temperature in the box using Arduino with both a fan and a heater, but im not sure how to implement PID to deal with sudden changes in temperature.

- You are using the AutoTuning version of the PID: this is not bad, but likely overkill here. Start with the SimplePID version to learn and understand…

- You are wiring the output of your PID to a "temperature chart": usually this is nonsense! The output of the PID is used to change an actuator in your control system and so described the actuator position/setting. What is the actuator in your system? Do you want to set a speed of your FAN?

- Learn about the "output range" input of the PID: here you can set a suitable output value range - suitable to your actuator!

- After reading those books mentioned above you should know about the meaning of those PID gain values: choose them suitable to your control loop…

- I often use PID to generate a PWM value (range 0-100%) for a heater: you can now switch on/off the heater in a PWM style. Depending on the control system I use PWM frequencies of just 0.05Hz (or full cycle of 20s)…

[TommyJ]

Hi Paddy,

Have you had any success with this. I am currently working on a similar Temp Control project and I am hitting the same road blocks.

[GerdW]

Hi Tommy,

I am hitting the same road blocks.

Then why don't you follow my suggestions?

When there are other "road blocks" then you should

- create your own thread

- show your VI

- explain the problems you got