Chapter 5 Using the SCXI-1141/1142/1143 Module
SCXI-1141/1142/1143 User Manual 5-4 ni.com
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.
Configuring Channel Properties
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.
Note You cannot adjust some properties while a task is running. For these properties,
youmust stop the task, make the adjustment, and re-start the application. Tables5-1
through 5-4 assume all properties are configured before the task is started.
Table 5-1. NI-DAQmx Voltage Measurement Properties
Property Short Name Description
Analog Input»Maximum Value 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.
Analog Input»Minimum 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.