Event-driven communication between cRio RT and Host

[ManfredAmann]

Dear LabView experts:

I'm using a cRio-9012 and LabView 8.2 to setup a high-speed data acquisition system. Data acquired by the FPGA is communicated to the RT by using FIFOs (Target to Host DMA) and interrupts. Since the bulk of data processing is carried out by the Host machine, I'm looking for a way to transfer the data from the RT to the Host in a similar fashion - either using some kind of interrupt mechanism or (preferably) an event-driven communication method. In order to prevent heavy CPU loading by using a while-loop and continuously polling some kind of trigger, an event-based structure would certainly be more elegant.

Thanks upfront for any help and guidance,

Manfred 

[AdnanZ]

Well, there are only limited protocols that you can use to communicate between Real-Time VI and the Host VI on a cRIO target. Those are shared variables, TCP, UDP and Datasocket. All of them support polling mechanisms. But, you could take advantage of the event-based mechanism if you are using shared variables to communicate between the two and have the LabVIEW DSC Module. With this setup, you may also have a VI running on a Windows system which responds to events for Shared Variables which are hosted on the Shared Variable Engine on a RT Target.

Have a look at the following:

Creating a Value Change Event for Shared Variables

There are also examples shipped with LabVIEW DSC that show you how to use events with shared variables. Do post back, if you have any questions.

[AdnanZ]

Check out this post I had responded to a while back:

http://forums.ni.com/ni/board/message?board.id=170&message.id=406710

[ManfredAmann]

Dear Adnan:

Thanks for your quick reply. Is there any chance you could convert the example you've attached to a version readable by LabView 8.2. I don't have 8.6 (yet) and thus cannot open your example.

Thanks again,

Manfred

[AdnanZ]

Sorry don't have DSC on this machine. You can check this video out:

Creating an Alarm Event Structure with the LabVIEW Datalogging and Supervisory Control Module 8