Programming instructions

© National Instruments Corporation 16-1 LabVIEW Data Acquisition Basics Manual
16
When You Need It Now—
Immediate Digital I/O
This chapter focuses on transferring data across a single port. The most
common way to use digital lines is with nonlatched (immediate) digital I/O.
All DAQ devices and SCXI modules with digital components support
this mode.
When your program calls a function in nonlatched digital I/O mode,
LabVIEW immediately updates the digital line or port output state or
returns the current digital value of an input line, depending on the digital
line direction. LabVIEW inputs or outputs only one value on each digital
line in this mode. You can completely configure port (and sometimes line)
direction in software, and you can switch directions repeatedly in a
program if necessary.
A typical example of when you might use nonlatched (immediate) digital
I/O is in controlling or monitoring relays. You can also use multiple ports
or groups of ports to perform digital I/O functions. In order to group digital
ports, you must use Intermediate or Advanced VIs in LabVIEW. You can
read more about grouping multiple digital ports in the next chapter,
Chapter 17,
Shaking Hands with a Digital Partner
.