How do we navigate between different VI's?

[TeamA]

HELP! We've been given this task to monitor this rig setup which is a setup of tanks and associated pipes, pumps and valves. We have loads of various inputs including things like tank levels, valve status, pump status and want to firstly monitor the whole thing. Further to this we have to setup a batch routine, e.g. fill tank 1 to 100, wait for 10 seconds, dump into tank 2 - batch complete. We have a whole host of stuff we need to have on the front panel and want to use various front panels - e.g. one to show the rig and it's status, one to have buttons to set off a batch run. Our query is how to navigate through such screens. We've looked at how to open VI's (open VI reference/property node/invoke node/close reference) but can't seem to find a way to close such screens. As this is a plant which is being constantly monitored, all VI's must be running continuously...

Here's what we would ultimately like to do: Have a main screen - an overview of the plant (displaying the status of it's devices) which contains a button to open a screen from which we can set off a batch run, then on the click of a button on this screen, it closes, and we return to the main screen.

Any help would be much appreciated!!!! 

P.S. We are very much LabView beginners, please be gentle!

[gwd]

A few thoughts:

- DON'T try to do this all at once, especially if you are a beginner. Work on, and test, pieces.

- Are there safety issues? Do you have or need independent interlocks, or can the system be designed to fail safe?

- Think about the issues of modal dialog boxes/ pop up VIs- if done wrong, the system will stop completely while waiting for user input. This could be bad.

[TeamA]

We really are beginners, we've had two weeks training and are supposed to understand how to achieve this task and get the project running within 6 weeks.

There is no major interlocks or safety issues as it is only a test rig.

[smercurio_fc]

If you open the Example Finder and enter "dialog" you will find a "Login Dialog" VI that is a popup with a Close button. It is setup as a dialog, but this can be easily changed from the VI Properties->Window Appearance.

An alternative approach if you want the stuff displayed all the time is to use subpanels. This embeds a subVI's front panel in a subpanel on a main VI. Another option is to use a tab control.

You need to think beyond how to popup windows. You need to think architecture, which is where 90% of your programming is going to be concentrated. The best approach for you is a producer-consumer architecture. Search this group for "producer consumer" and you'll come up with many examples.

This may seem like a cop-out answer, but your manager needs to seriously consider hiring an experienced LabVIEW developer who has done plant automation to act as a consultant and guide you. Anytime you're dealing with hardware there are always safety issues, even if you don't think there are. When you say "there is no major interlocks", that scares me.

What you're describing isn't overly difficult, but for someone who's just starting out it can be overwhelming, especially if you have no prior programming experience. And I don't mean LabVIEW experience - I mean basic programming knowledge and experience. 90% of the problems people have programming in LabVIEW is that they simply don't know how to program in the first place.

Message Edited by smercurio_fc on 06-20-2007 09:21 AM

[johnsold]

gwd is right.

Do a lot more thinking and planning right now than LabVIEW coding. Make sure you can describe exactly what the software is to do at any time before starting to write that software.

Look at the Producer/Consumer Design pattern examples which ship with LV. You will probably want a state machine architecture based on or similar to these examples.

I like tab controls for user interface for systems like yours. You can hide the tabs and control which tab page is showing from the software. This avoids some of the pop-up and modal issues. It does not relieve you of thinking about the navigation.

Build a test program which has only user interface and very simple behind the scenes logic to test your UI ideas.

Good luck. It sounds like a big task for beginners.

Lynn