Shared USB port execution

[Dan10]

Hi:

I use a USB to RS-232 (8x) hub and I created a SubVI to read data via a COM port using VISA. Everything works fine.

When I try to execute two instances of the same SubVI in parallel (by putting two instances of the same VI on the block diagram with different COM ports as inputs), the SubVIs do not execute at the same time but sequentially. Which settings will allow to execute the SubVis in parallel and share the USB port?

Thanks!

Dan

[Albert.Geven]

Please remeber that USB is also a serial line so two ports on the same usb bus never can run simultaneously

[TeaAndBiscuits · Accepted solution]

Hi Dan10

Have you tried

" VI>>Properties>> Excecution >> Reentrant Execution(Checked) " ?

You should be able to communicate with 

- different instances of the same program(VI) on the different ports...does not matter USB, serial, GPIB.

Does this work for you?

(On the other hand you want to access the same port, then you may have to isolate your 2 instances (as GUIs) talking to the same underneth driver resource.)

[Dan10]

Great. It works.

Thanks!