Avoid "downloading to target" message using FPGA

[Microscope Man]

Greetings.

When I use my main labview program to call a command on a compiled FPGA program on my NI-7831R, a box comes on the screen saying: "downloading vi to target" which takes only several milliseconds.  The funny thing is this did not happen before, and just the last time I compiled my FPGA program it began happening.   Compilation should automatically download the program to the card, so I am not sure where I went wrong.

Any advice would be highly appreciated.  Thanks so much.
Richard Cisek
rcisek@utm.utoronto.ca

[DuffmanSays]

Hello Richard,

This message will not show up when the host VI connects to an FPGA VI that is already running. I also do not recall seeing this message when the previously downloaded bitfile is run on the same target. In any case, we'd like to be sure that what you are seeing is normal.  

You mentioned that you "call a command on a compiled FPGA program" in order to run the FPGA VI. By this do you mean that you are using the Open FPGA VI Reference node? In this node do you specify the FPGA VI from the project or do you point to the compiled bitfile? In the close VI reference, do you close and reset? Has anything changed on your host program since this VI was last compiled? Thanks very much for these details.

Mike D.

[Microscope Man]

Hello.

The problem went away for a while so I didn't reply, sorry.

Here is the problem, and sort of solution which is why I didn't reply for a bit.  Here is what happenes.  Right after I compile the FPGA vi, when I use the host vi to perform functions on a non-running FPGA vi, such as run, stop, reset... any function, a diolg box comes up saying "Downloading vi to target" and this takes about 1/4s each time I run any fpga vi command in the following manner:
in my host vi I:
1. Open reference (not run) to the FPGA VI (not bitfile)
2. Invoke Method: Reset
3. Close Reference (not reset)

when I do this, the dialog box comes up.

I found a fix for it too!  If I second-click on the fpga-vi in the project explorer and click on download to target, the system freezes, when I reboot and run the dialog boxes no longer show up... until the next time I compile.

Strange non?  I am using Labview 8.01 with PCI7831R
.
Perhaps you can explaiin it, perhaps not.

Richard Cisek

[DuffmanSays]

Hello Richard,

I am surprised by the fact that your system hangs when right-clicking and downloading to the target. This is definitely not expected behavior. Does this happen for any VI that you attempt to download? I might suggest repairing the FPGA module on this machine. I can help with resolving this behavior if you'd like to dig further into it.

In terms of the dialog that mentions your VI is being downloaded, the FPGA software keeps track of when this download is required. After paying attention to when this dialog shows up, I have determined that the first run of your code after a fresh compile will cause this download window. Subsequent runs of unmodified code do not cause the code to download before it is executed. This is always when referencing an FPGA VI that is not running and performing any interface with this FPGA VI reference. If this is not the behavior that you are seeing, then I cannot say for sure why you have observed different results. If you are concerned about this download dialog, please post back and we can discuss this further. Thanks.

Mike D.