Updating input on RT without polling

[PTLanza]

I am using a compactRIO real-time controller with RT 8.2 and LabView 8.2.   I have a VI set up on the host computer that interfaces the user with the real-time VI.  I have just learned how to use event structures to update itself only when there is front panel action on the specified control buttons so that no polling is involved.  I am passing the information to the real-time module using a shared-variable so that it can update the FPGA digital output module, however this is still using a loop that is iterating and updating the FPGA every second.  I would really like to get rid of this loop and replace it with some kind of code so that this part of the RT vi only executes when a value is changed from the host computer to eliminate polling, just like using an event structure, only there is no control that is changing.  All of these values are booleans, if this makes anything easier.  How can I go about making this happen?  Thanks.

[Jason_Whaylen]

Hi PTLanza!

Thanks for contacting National Instruments.  From the information you have provided, I understand why you would want to achieve this type of functionality.  This article I found directly relates to the question you have posed.  Unfortunately, this type of operation isn't possible for some important reasons.  In general, event based programming is not an effective method in Real-Time because it can kick the program out of a time critical operation.  Therefore, it would essentially result in an increase in jitter.

I hope this helps!  Let me know if you have other question or need clarification.  Have a great day!

Jason W.