Need some help with starting my LV project...

[shift2DeMax]

Hello,  I am a newcomer to Labview and needed some advice to start a project that conditions NiMH batteries.  Basically I need a Home screen that shows 8 stations, each station showing different indicators of info.  Each station has 12 temperature readings so I need a button to go to a small screen that shows the temperature readings plus another button that shows status of relays. 

Do I use a cluster to put all the indicators for each station and another cluster for the two buttons? 

Can I use a case struct for each different station with a while loop around that to go from one station to the next?  Can one case interact with another case?

Can I use an event struct with the buttons to go to the small info screens and how can I go back to the Main screen? 

Any help would be appreciated.  Thanks.


Have a good Labor Day Weekend!

[jjcimon]

what is the sampling rate of the temp readers and relays?

to answer your question it is important to know sampling rate, a little more about the process.

jacques

[shift2DeMax]

I believe the sampling rate for the temp. sensors is 100 mps. 

Basically, we will have 8 large NiMH batteries in sequence and will charge them and discharge them to condition them for use.  We will be reading voltages and currents.

Thanks for any help.

Message Edited by shift2DeMax on 09-04-2007 09:10 AM

Message Edited by shift2DeMax on 09-04-2007 09:31 AM

[shift2DeMax]

***Correction: Actually the sampling rate for the temp. sensors is 1 per second and we will use CAN for communications.

Message Edited by shift2DeMax on 09-04-2007 11:17 AM

[Yi Y]

Hi shift2DeMax,
The "small screen" you are thinking about would probably be something like a subVI that has the front panel showing. You can set up a case structure that calls the subVI when the button is clicked. See attached VI of an example of how that's done. Right click on the subVI and go to subVI node set up to set up how the subVI is going to be called. One case cannot interact with other cases of the same case structure. You have to plan out if you want your program to have a state machine or not. Please take a look at the State Machine template that comes with LabVIEW on how to make a simple state machine. If you have LabVIEW 8.5, try out the state chart module to work with a state machine. As for if you should put indicators into a cluster, that's up to your preference and program architecture. Cluster in LabVIEW is like structs in C. If you are using data in a subVI and passing a lot of data in and out of a subVI, it might be a good idea to use clusters to avoid too many input and output terminals.

Yi Y.
Applications Engineer
National Instruments
http://www.ni.com/support

Message Edited by Yi Y on 09-04-2007 08:13 PM

Message Edited by Yi Y on 09-04-2007 08:14 PM

[shift2DeMax]

Thanks Yi Y for the thorough explanation on how to go from one screen to another by pressing a button.  I just had one question.  Is it easier or better to use case structures then event structures for this process?  Just wondering why case structs where chosen.

Thanks.

[Yi Y]

Hi shift2DeMax,

Event Structure is a blocking call, which means when an event is executing, nothing else is executed.  Event structure is usually used when the code that needs to be executed in it is very simple and doesn't last for very long.  I used the case structure because I wanted to demonstrate that the code in your main VI can still be executing while your small pop up window is open.

Yi Y.
Applications Engineer
National Instruments
http://www.ni.com/support