National Instruments SCXI -1125 用户手册

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Chapter 5    Using the SCXI-1125
© National Instruments Corporation
5-7
General Discussion of Typical Flowchart
The following sections discuss briefly considerations for a few of the steps 
in Figure 5-1. These sections give an overview of some of the options and 
features available when programming with NI-DAQmx.
Creating a Task Using DAQ Assistant or 
Programmatically
When creating an application, first you must decide whether to create the 
appropriate task using the DAQ Assistant or programmatically in the ADE.
Developing your application using DAQ Assistant gives you the ability to 
configure most settings such as measurement type, selection of channels, 
excitation voltage, signal input limits, task timing, and task triggering. You 
can access the DAQ Assistant through MAX or your NI ADE. Choosing to 
use the DAQ Assistant can simplify the development of your application. 
NI recommends creating tasks using the DAQ Assistant for ease of use, 
when using a sensor that requires complex scaling, or when many 
properties differ between channels in the same task.
If you are using an ADE other than an NI ADE, or if you want to explicitly 
create and configure a task for a certain type of acquisition, you can 
programmatically create the task from your ADE using functions or VIs. 
If you create a task using the DAQ Assistant, you can still further configure 
the individual properties of the task programmatically with functions 
or property nodes in your ADE. NI recommends creating a task 
programmatically if you need explicit control of programmatically 
adjustable properties of the DAQ system.
Programmatically adjusting properties for a task created in the DAQ 
Assistant overrides the original, or default, settings only for that session. 
The changes are not saved to the task configuration. The next time you load 
the task, the task uses the settings originally configured in the DAQ 
Assistant.
Adjusting Timing and Triggering
There are several timing properties that you can configure through the 
DAQ Assistant or programmatically using function calls or property nodes. 
If you create a task in the DAQ Assistant, you can still modify the timing 
properties of the task programmatically in your application.
When programmatically adjusting timing settings, you can set the task to 
acquire continuously, acquire a buffer of samples, or acquire one point at a