National Instruments Module SCXI-1125 - Manual (Page 53)

Chapter 5 Using the SCXI-1125
SCXI-1125 User Manual 5-16 ni.com
Traditional NI-DAQ (Legacy) in LabVIEW
LabVIEW is a graphical programming environment for test and
measurement application development with built-in easy to use tools for
data acquisition, analysis, and display. You can use functional graphical
blocks called subVIs to easily create a custom application that fully utilizes
the SCXI-1125 programmable functionality. Traditional NI-DAQ
(Legacy) provides several standard data acquisition subVIs as well as
subVIs specifically for use with the SCXI-1125.
For applications using Traditional NI-DAQ (Legacy) in LabVIEW, there
are two typical methods of addressing SCXI-1125 channels—virtual
channels (specifically virtual channels) and SCXI channel strings.
Depending on the needs of your application, you choose one of these
channel addressing methods to use in your LabVIEW application.
When you use virtual channels, the maximum number of channels per
E Series DAQ device is 512 in multichassis systems. NI recommends using
the virtual channel for ease of use. Refer to Appendix B,
Using SCXI
Channel Strings with Traditional NI-DAQ (Legacy) 7.0 or Later , for more
information on how to create a virtual channel.
The SCXI channel string allows you to combine large numbers of channels
into fewer scan list entries, to measure the signal voltage level directly for
custom scaling, and to dynamically perform an offset null compensation in
your application. NI recommends using SCXI channel strings for more
advanced applications. In LabVIEW, an array of these channel strings
configures multiple modules for scanning. When using SCXI channel
strings, you can scan up to 3,072 channels in a multichassis system using a
single E Series DAQ device.
Note You cannot mix virtual channels with the SCXI channel strings within the same
channel string array.
To use virtual channels, enter the name of a virtual channel into the analog
input channel string. If using multiple virtual channels, enter them in a
different index in the channel string array, or separate them using a comma.
Since you can randomly scan analog input virtual channels, you can enter
the virtual channels you want to scan in any order or repeatedly in a channel
string array.