National Instruments 1142 用户手册

When programmatically adjusting timing settings, you can set the task to 
acquire continuously, acquire a buffer of samples, or acquire one point at a 
time. For continuous acquisition, you must use a while loop around the 
acquisition components even if you configured the task for continuous 
acquisition using MAX or the DAQ Assistant. For continuous and buffered 
acquisitions, you can set the acquisition rate and the number of samples to 
read in the DAQ Assistant or programmatically in your application. By 
default, the clock settings are automatically set by an internal clock based 
on the requested sample rate. You also can select advanced features such as 
clock settings that specify an external clock source, internal routing of the 
clock source, or select the active edge of the clock signal.

All ADEs used to configure the SCXI-1141/1142/1143 access an 
underlying set of NI-DAQmx properties. Table 5-1 shows some of these 
properties. You can use Table 5-1 to determine what kind of properties you 
need to set to configure the module for your application. For a complete list 
of NI-DAQmx properties, refer to your ADE help file.

You cannot adjust some properties while a task is running. For these properties, 

you must stop the task, make the adjustment, and re-start the application. Tables 5-1 
through 5-4 assume all properties are configured before the task is started.

Table 5-1.  NI-DAQmx Voltage Measurement Properties

AI.Max

Specifies the maximum value 
you expect to measure. The 
SCXI-1141/1142/1143 gain and 
E/M Series DAQ device range 
are computed automatically 
from this value.

AI.Min

Specifies the minimum value 
you expect to measure. The 
SCXI-1141/1142/1143 gain and 
E/M Series DAQ device range 
are computed automatically 
from this value.