9871 FPGA serial download cause error -65536

[jjacob95]

Hello

I am working with a CRIO-9047 with multiple SCAN modules and a 9871 for serial communication. I run in hybrid mode, interactive mode (for the FPGA) and use the “NI-987x Serial Loopback.lvproj” for the FPGA implementation.

Now, periodically (~50ms) I use the serial communication to enquire about the status of external hardware, this works flawlessly with a fast response of about 10 bytes. Also if I disable my real-time loop (containing scan-engine) the problem is non existent, so by itself there is nothing wrong with the serial.

However, the problem ensues when I try to download a package of data, in this case 4006 bytes. Executing the download will cause the SCAN engine to crash with the error code -65536, or at least this is what I think happens. (Debugging has been exceedingly difficult for some reason) If I run some of the code in "Highlight executing" mode I can avoid crashes, but I believe this is incidental. I've tried inserting wait functions where I've thought I had "greedy loops". I can not seem to get a grasp of what the problem actually is. 

My intuition is that I have a memory integrity error or I am overloading a CPU with a greedy loop.

I would very much like someone else's opinion on this matter.

Kr Jonas

[jjacob95]

I have attempted to set up a synchronization between the FPGA and the Scan engines scan cycles (Attached) however this does not seem to do anything. I am really at my wits end here, having tried everything else I could think of.

It is very clear to me that the FPGA crashes the Scan engine, as I get the errors -65536 and/or -65589, that seem to indicate the scan engine is not deployed (ie. it crashed). Surely I am not the only one who have attempted to run a 9871 serial communication with large data packages while running in hybrid mode?

Kr Jonas

[jjacob95 · Accepted solution]

The issue was related to synchronisation of the Scan engine and the FPGA, which caused the FPGA to run terribly slow.