Beijer Electronics (formerly QSI Corporation)

Hello,



I have an application on a G70 that has 5 tabs in a tab container. When I go to write to a checkbox from LabVIEW, the checkbox does not switch states if it is on a different tab than the one that is already displayed. This causes my LabVIEW program to hang, since it is looking for the checkbox on the Q70 to be checked before continuing on - if it doesn't see the right answer, it tries again and again...



Is there an easy way to accomplish what I am trying to do? Am I missing something about tab containers in general?



Thanks in advance.

You can think of each tab as a screen. Whenever a screen is disabled the objects in the screen are disabled. When new channel data is received all enabled objects are notified. Meaning that the checkbox within the disabled tab is not notified of the change in that channels value. There are a couple of ways to handle this.



1. You could change the NIComV2 object to notify all objects of new channel data regardless of wether they are disabled or not. The problem with this is that performance could be drastically hurt, so I wouldn't take this approach.



2. Basically you need to make sure that if an object is required to recieve data at any time (disabled or not), then it needs to be enabled at all times. The only way to do this is to put the object in globals.



2a. One approach that I think would require little work is to make a copy of your NICheckBoxV2 object, move the copy into globals, and move it off to the side so that its non-visible. This way if your Tab is disabled you'll still have an object in globals that will recieved the channel data.



2b. Another alternative solution is use an NIVirtualVariableV2 in globals, and a normal CheckBoxV2 in the tab instead of an NICheckBoxV2. When the NIVirtualVariable receives an update on that channels its NewChannelData() will be called. You can put code in the NewChannelData event to update the CheckBoxV2 and take any other needed actions. The code might look something like this:







Unfortunately I recently fixed a bug in the NIVirtualVariableV2 object that you'll need to fix also. I wouldn't normally reccomend editing a library directly, but in this case its okay. You can either make this change via a template or editing the library directly. Find the channeldata function in the NIVirtualVariableV2 object source and replace it with this code.

_________________
Ron L.

http://www.beijerelectronicsinc.com/

Ok,



Could I use a single global instead? That is, have LabVIEW write to a global object (holds the desired tab name or number) which is then polled somehow to determine what tab should be active?

You can have Labview change tabs that way. Have a global object that whenever a numerical value was recieved it would select/change the active tab based on that value.



You could also put code in your application to send a numerical value to labview whenever a tab is changed so that labview can keep track of what tab is enabled.



An NIVirtualVariableV2 in globals would work for this.

_________________
Ron L.

http://www.beijerelectronicsinc.com/

Ok. Regarding virtual variables, could you clarify the description (in the documentation and when you hover over it)? It appears to be missing a word. The last sentence reads:

To assure that the data is sent over the correct channel, it is suggested that the channel is immediately before each time data is assigned to any of this objects data properties.



Is a word missing here?



Thanks.

That was some confusing documentation. Here's what I've changed it to:



This object provides a simple method of sending and receiving a value of different types over the communications channel. The data is sent on a channel when a value is assigned to any of the data properties. To assure that the data is sent over the correct channel, the channel property should be updated (if different) before a value is assigned to any of this objects other properties.



Hopefully this makes more sense.

_________________
Ron L.

http://www.beijerelectronicsinc.com/

OK... thanks for everything!