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Chapter 5 Using the NI PXI-4224
NI PXI-4224 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 and buffered acquisitions, you can set the acquisition
rate and the number of samples to read. 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, the internal routing of the clock source, or that select
the active edge of the clock signal. You can also specify whether or not to
start the acquisition using a start trigger signal.
Configuring Channel Properties
All of the different ADEs used to configure the NI PXI-4224 access an
underlying set of NI-DAQmx properties. Table 5-1 lists of some of the
properties that configure the NI PXI-4224. You can use this list to
determine which properties you need to set to configure the device for your
application. If you created the task and channels using the DAQ Assistant,
you can still modify the channel properties programmatically. For a
complete list of NI-DAQmx properties, refer to your ADE help file.
Note Table 5-1 is a representative sample of important properties you can adjust in analog
input measurements with the NI PXI-4224. It is not a complete list of NI-DAQmx
properties and does not include every property you may need to configure the device. For a
complete list of NI-DAQmx properties and more information about NI-DAQmx properties,
refer to your ADE help file.
Table 5-1. NI-DAQmx Properties
Property Short Name Description
Analog Input»
General Properties»
Input Configuration»
Coupling Property
AI.Coupling DC—Allows NI-DAQmx to measure the
input signal.
GND—Removes the signal source from the
measurement and measures only ground.
Analog Input»
General Properties»
Gain
AI.Gain Specifies the gain of the isolation amplifier.
For the NI PXI-4224 you can specify
1 or 10.
Analog Input»General
Properties»Advanced»
High Accuracy Settings»
Auto Zero Mode
AI.AutoZeroMode Specifies when to measure ground.
NI-DAQmx subtracts the measured ground
voltage from every sample.