I assume that LinuxCNC and LabView are not running on the same PC?
Is this conventional LabView or LabView Realtime? (if that even still exists).
(As an irrelevant aside, until last year LabView RT was the only thing that I had actually been paid to program in)
Have you considered not using the NI card for linuxcnc control, but instead communicating with LinuxCNC using linuxcncrsh?
linuxcnc.org/docs/stable/html/man/man1/linuxcncrsh.1.html
