Chapter 2
Installation and Configuration
©
National Instruments Corporation
2-17
In Traditional NI-DAQ, you configure virtual channels using MAX. In
NI-DAQmx, you can configure virtual channels with the DAQ Assistant,
which you can open from MAX or your application software. You also can
configure virtual channels with the NI-DAQmx API in your application
program.
A
task
, an important new concept for NI-DAQmx, is a collection of one
or more virtual channels with timing, triggering, and other properties.
Conceptually, a task represents a measurement or generation you want to
perform. You can set up and save all of the configuration information in a
task and use the task in an application.
In NI-DAQmx, you can configure virtual channels as part of a task or
separate from a task. Virtual channels created inside a task are
local
channels
. Virtual channels defined outside a task are
global channels
. You
can create global channels in MAX or in your application software and then
save them in MAX. You can use global channels in any application or add
them to a number of different tasks. If you modify a global channel, the
change affects all tasks in which you reference that global channel. In most
cases, it is simpler to use local channels.
Configure a Task in NI-DAQmx
Configure tasks with the DAQ Assistant. You must have version 7.0 or
later of an NI application software package to create tasks and channels
with the DAQ Assistant.
•
In MAX, right-click
Data Neighborhood
and select
Create New
.
In the
Create New
window, select
NI-DAQmx Task
and click
Next
.
•
You also can open the DAQ Assistant directly from within
NI application software.
–
In LabVIEW, there are several ways to open the DAQ Assistant.
•
Drop the DAQ Assistant Express VI from the Express Input
palette, as described in the
Getting Started with LabVIEW
document.
•
You also can use the DAQmx Task Name control to open the
DAQ Assistant. Right-click the control and select
New Task
.
The
Taking an NI-DAQmx Measurement in LabVIEW
tutorial
has step-by-step instructions on how to create a task from the
DAQmx Task Name control and generate code for the task.
In LabVIEW, select
Help»Taking an NI-DAQmx
Measurement
to open the tutorial.
