© National Instruments
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NI cDAQ-9132/9133/9134/9135/9136/9137 User Manual
Getting Started with DO Applications in Software
You can use the cDAQ controller in the following digital output applications:
•
Single-point (on-demand) generation
•
Finite generation
•
Continuous generation
For more information about programming digital output applications and triggers in software,
refer the
LabVIEW Help
or to the
NI-DAQmx Help
.
Digital Input/Output Configuration for NI 9401
When you change the configuration of lines on a NI 9401 digital module between input and
output, NI-DAQmx temporarily reserves all of the lines on the module for communication to
send the module a line configuration command. For this reason, you must reserve the task in
advance through the DAQmx Control Task before any task has started. If another task or route
is actively using the module, to avoid interfering with the other task, NI-DAQmx generates an
error instead of sending the line configuration command. During the line configuration
command, the output lines are maintained without glitching.
PFI
You can configure channels of a parallel digital module as Programmable Function Interface
(PFI) terminals. The cDAQ controller also provides one terminal for PFI on its front panel. One
or two digital modules can be used to access the cDAQ controller PFI terminal. You can use the
the cDAQ controller PFI terminal to wake the controller from a low power state. You can drive
a wake event with high logic-level signals. Refer to the specifications document for your cDAQ
controller for DC input characteristics.
You can configure each PFI individually as the following:
•
Timing input signal for AI, AO, DI, DO, or counter/timer functions
•
Timing output signal from AI, AO, DI, DO, or counter/timer functions
PFI Filters
You can enable a programmable debouncing filter on each PFI signal. When the filter is enabled,
the controller samples the inputs with a user-configured Filter Clock derived from the controller
timebase. This is used to determine whether a pulse is propagated to the rest of the circuit.
However, the filter also introduces jitter onto the PFI signal.
The following is an example of low-to-high transitions of the input signal. High-to-low
transitions work similarly.
