Labview help needed

[cunnie85]

Really struggling and need help with the below project.
using a case structure how do i monitor a heating system manually and automatically using temperatures from a demo VI?

In automatic mode the system will monitor the ambient temp and depending on the value will switch the heater on or not. the heater is switched on when the temp falls below the low temp setpoint. When the heater is switched on the system will add a value to the measured temp to show the temp rising, when the temp reaches the high temp setpoint the heater switches off.

In manual mode the heater will be on whenever the heater on/off switch is on. The system will monitor the heater on/off condition at all times.

The front panel should include:

- Indicators
AC on/off
Heater on/off
Manual or Automatic operation
current temperature reading
Historical temperature reading (Chart)

- Controls
AC on/off
Heater on/off
Manual or Automatic
Temperature setpoint control low- to switch heater on
Temperature setpoint control high- to switch heater off
-Coding

Use a case structure to control manual and automatic operation.
Use a case structure in decision making e.g. when deciding to switch heater on or off.

[JamesBrown]

Originally Posted by cunnie85

really struggling with this project
using a case structure how do i monitor a heating system manually and automatically using temperatures from a demo VI?

As a disclaimer, this site was created for the FIRST Robotics Competition, and most people in these forums are here for that reason. That said there are many experienced LabView programmers on here and someone may be willing and able to help.

Post what you have so far, a screenshot of your code is often easiest for LabView.

If you have not started try to sketch it out on paper or describe the functionality with psuedocode. No one here will hand you the right answer, the majority of us are teachers and engineering mentors, so we aren't in the business of doing someone's homework for them, however we are happy to teach.

[Tungrus]

I believe the temperature control project is one of the NI training project.

Anyways, FRC teams would be more than happy to guide you, even if you are not in FIRST family!

[cunnie85]

Hi guys,
Thanks for the reply here s what I have done so far I know I have to add case structures but Im not sure where to go from here. Program and screenshot attached

[Chadfrom308]

I forgot, and am not 100% sure, but I think that you need to put all the switches and indicators inside the while loop. That is, if you want them to update while the while loop is running.

To switch from automatic to manual, I would put a case block/loop, plug the "manual mode" switch into the t/f statement. In there you could do the manual and automatic functions (there are 2 cases in this case, true and false, true being manual mode and false being automatic).

Inside the manual, you would put some sort of code that would increment/decrement system that would increase or decrease the temperature over time based on whether AC is on or heat is on (maybe another case statement?). For the false (Automatic case) you would make a comparator (less than or greater than... that sort of stuff) that would check to see if you need to turn the AC or heater on. You would then turn either the AC on or the Heater on based on the comparator (again, maybe another case structure here).

I am not really good with graphing stuff in labview, I would assume you could just create a graph and push the results to the graph every iteration of the while loop, but it is probably more complicated for that.

I am assuming that this is for a class, so I am not giving you the detailed answer, I wouldn't want to spoil the fun

Also, as an added bonus, you can create property blocks that let you change the properties of certain things (like text color on an indicator). If you explore those properties, you can find the disable property. You can disable manual controls in automatic mode, for example.

Hope this helps get you started! If you need any more help, just ask!

[cunnie85]

Thanks Chad,

I have added a case structure, when true(manual mode) the program runs constantly, when false(automatic mode) it also runs constantly however when the temp drops below 28 deg it turns off an LED on my front panel. Im having problems getting the heater to turn on automatically when the temp falls below a certain value. program attached

[Chadfrom308]

You could put a "less than" or "less than or equal to" comparison block and put a constant of 28 and hook it to the top and the temperature to the bottom, then you could do an "or" logic block and hook that up to however you have it set up. I don't have labview at work, so it when I get home, if you need me to, I will look at it some more and help

[cunnie85]

Yes please that would be great.

[Chadfrom308]

I sent you a message a couple of days ago, let me know what you think

[cunnie85]

Hi Chad can you take a check out my program from the previous mail on Labview, I have a comparison block added and set to 28 but I'm a bit confused now so if you could have a more detailed look that would be great.

[cunnie85]

Demo temp