I have a VI that has two main "recording" loops. One read FPGA data and other reads USB serial device data. Since VI also contains other parts of the code (updating GUI, event handler etc) there are sometimes strange behaviours (delays) in "USB recording loop". My quiestion is if there is any way to tell LV that it must execute USB reading loop in "High priority" maner so that it can't be interrupted and it must execute in a more stable way? In other languages like c, c++, delphi there is a "Thred" you can define and open to run on a specific processor with "High" priority parameter.

LabVIEW

How to set High priority execution on part of block diagram

I see your code is enqueuing data even when there isn't any (bytes at port = 0). You should move the enqueue into where you are receiving data. And that's the other thing. Even though that is the way the (ugh) LabVIEW example shows you how to do it, using bytes at port to decide how many bytes to read is a dangerous thing because if the amount actually changes in between bytes at port and the serial read, you'll miss some data if it is the last read. Maybe this is what is causing the USB loop to seem to have delays? there's always a better way than this, but how you do it depends on ho the messages arrive.

Bill

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