National Instruments SCC-68, Руководство пользователя

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© National Instruments Corporation 29 SCC-68 User Guide
Configuring Channels and Tasks
This section applies only if you are programming the device using
NI-DAQmx or NI application software.
A physical channel is a terminal or pin at which you can measure or
generate an analog or digital signal. A virtual channel is a collection or
settings such as a name, a physical channel, input terminal connections, the
type of measurement or generation, and can include scaling information.
In NI-DAQmx, virtual channels are integral to every measurement. In
NI-DAQmx, use the DAQ Assistant, accessible from MAX or NI
application software, to configure virtual channels and measurement tasks.
Refer to the
DAQ Assistant Help and the Measurement & Automation
Explorer Help for NI-DAQmx . You also can configure virtual channels with
the NI-DAQmx API in your application program.
A task , an important 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 virtual
channels . Virtual channels defined outside a task are global virtual
channels . You can create global virtual channels in MAX or in your
application software and then save them in MAX. You can use global
virtual channels in any application or add them to a number of different
tasks. If you modify a global virtual channel, the change affects all tasks in
which you reference that global virtual channel.
Configure a Task
When using NI-DAQmx, configure tasks with the DAQ Assistant. To
create tasks using the SCC-68, you must have NI-DAQmx version 8.1
or later.
• To launch 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 . If you are using a remote RT
target, expand your target, then right-click Data Neighborhood and
select Create New .
• You also can open the DAQ Assistant directly within NI application
software. Refer to the help of your software package for more details.