Chapter 4
Programming
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National Instruments Corporation
4-3
scy is the SCXI chassis ID, where y is the number you chose when
configuring your chassis.
mdz is the slot position where the module is located, with z being the
particular slot number. The slots in a chassis are numbered from left to
right, starting with 1.
Note
Note that the
ob
x
!
specifier is optional and causes the gains on the module and
DAQ device to be automatically set to fit the input limits parameter. When this specifier is
omitted, the default gain on the DAQ device, usually the lowest gain, is used.
The last parameter, channels, is the list of channels scanned for module z.
It can have several formats:
•
ob
x ! scy ! mdz !
n, where n is a single input channel.
•
ob
x ! scy ! mdz !
n1:n2, where n1 and n2 represent a sequential
list of input channels, inclusive.
LabVIEW and the Virtual Channel String
For LabVIEW, BridgeVIEW, Measure, and Visual Basic, the channel
string can also contain virtual channels. For the SCXI-1104/C, these virtual
channels are analog input channels you create that have custom names,
called tags in BridgeVIEW, and perform scaling and linearization
transparently without additional programming effort. Virtual channels are
useful when sensors requiring different scaling factors are connected to the
same SCXI-1104/C channel at different points in time. Using virtual
channels, you can use sensors needing special scaling in a generic analog
input application without performing hard-coded scaling or linearization.
If the scaling changes or you want to connect a different sensor to your
SCXI-1104/C, no changes are needed in the application. All you need to do
is create a different virtual channel and use its name in the channel string.
Note
You cannot mix virtual channels with the SCXI channel strings shown in
.
To create a virtual channel for the SCXI-1104/C, insert a new analog input
channel in the Data Neighborhood path in Measurement & Automation
Explorer, name it, and follow the prompts to create a customized analog
input channel. For more information about virtual channels, consult the
Measurement & Automation online help file.