FPGA memory from inside SubVI

[astromike]

In an FPGA application I am trying to get compiled, there are multiple subVIs which have their own VI scoped memory elements.  The main VI triggers off a large series of subVIs from inside an SCTL, and several of these subVIs contain VI scoped memory elements.  The individual subVIs compile fine, but when I go to compile the parent VI, I receive the error stating that memory reads must be followed by an uninitialized feedback/shift register.  When I go to add the feedback nodes, I cannot add them because the subVI does not have a loop in it.  Is it possible to have VI scoped memory in a subVI that is called from inside an  SCTL?

[JerryAL]

Hi

What version of LabVIEW and LV FPGA are you using?

This is a limitation that needed to be worked around, and required me to minimize my use of subVIs when using memory reads.

The good news is that the situation has been intentionally improved for LabVIEW 8.5 so that shift registers/feedback nodes can be placed on the diagram without being tied to a loop.

Jerry

[astromike]

I'm using LabVIEW 8.2.1 and LV FPGA 8.2.1.  The IF-RIO board that I am using is the NI-5640R IF Transceiver.  I understand that this board is not compatible with 8.5.  Is this just LV FPGA 8.5?  Can I use LV 8.5 and LV FPGA 8.2.1 together to accomplish placing the feedback nodes into the FPGA subVIs?

[JerryAL]

Ooops…  First day back after a 2 week vacation and didn’t realize that the driver support for the NI 5640R and LabVIEW 8.5 hadn’t been released yet.

Although it isn’t live on the web yet, the new installer is complete and waiting for the processes to go through to make it visible on NI’s normal driver download page.  It can be downloaded directly from here:
ftp://ftp.ni.com/support/rf/ni-5640r/driver/1.2/

If you have LabVIEW 8.5 and LV FPGA 8.5, save a copy of your project files before opening them up in LabVIEW 8.5.

Additionally, there were some significant changes in LV FPGA from 8.2.1 to 8.5. This will impact the NI 5640R VIs that are part of a LabVIEW library (.lvlib) in the project.  If you open your project and files and have errors, you need to swap out files with new ones from one of the example projects from the new driver.  I don’t have specific detailed instructions yet, but the basic part of opening a project created in LabVIEW 8.2.1 is to swap out the lvlib with one from one of the new shipping examples.  This involves opening one of the examples, renaming the project and files to the same names as your LabVIEW 8.2.1 project files.    Then copy the NI-5640R VIs directory to your 8.2.1 project directory, and then open your project files in LabVIEW 8.5.

Jerry

[astromike]

Jerry,

The zip file you linked me to appears to be password protected.  Where do I need to go to get the password?

Thanks,
Mike

[Dragis]

The issue has been greatly improved in LabVIEW 8.5 and LabVIEW FPGA 8.5 with the new floating feedback (feedforward) nodes, but for LabVIEW 8.2.1 you can simply wrap the memory portion of the code in your subvi in a while loop with a constant true wired to the stop terminal. You can then create an uninitialized shift register and pass the output of the shift register to the rest of the diagram just as you did before.

[astromike]

Dusty, I have tried that.  The problem in doing this is that you cannot place a while loop inside a Single Cycle Timed Loop, which the subVI is called from.

Thank you though.


Message Edited by astromike on 01-03-2008 01:44 PM

[JerryAL]

Hi Mike

Sorry about that.  Can you try the ni5640R 1.2.0f3.zip file?  I just verified that it is not password protected.

Jerry

[Dragis]

Ah, your right, its been a long week 🙂

[astromike]

That second file is quite a bit bigger, but I was able to unzip it.  Thank you, now to get IT in here to install 8.5.