National Instruments Measure Data Acquisition - Manual (Page 25)

Chapter 3 Using SCXI with Measure DAQ
Measure Data Acquisition User Manual 3-2 © National Instruments Corporation
your data acquisition device. The multiplexed mode is the default and
recommended mode to use with SCXI. In the parallel mode, each SCXI
module is directly connected to one data acquisition device and each
analog input channel on a SCXI module is connected to a separate
analog input channel on the data acquisition device. Not all data
acquisition devices or SCXI modules support the parallel mode.
Consult your data acquisition hardware user manual for more
information.
SCXI Analog Input
To configure channels on a SCXI analog input module in the DAQ task
configuration, first select the DAQ device in the main DAQ Tasks
dialog box to which the SCXI module is directly or indirectly
connected. Then, select the AI button to create an AI task or the Edit
button to modify an existing AI task. In the Analog Input
Configuration dialog box, specify the SCXI channel(s) you want to
acquire in the Channels field by entering a channel string. This channel
string provides information about the DAQ device channel, SCXI
chassis number, SCXI module number, and SCXI channel number. The
channel string has the following format:
ob0!scx!mdy!z
In the SCXI channel string, x represents the chassis number, y the
module number, and z the channel number.
‘ ob0 ’ in the SCXI channel string indicates which onboard channel (on
the DAQ device) to use to acquire the data. In the SCXI multiplexed
mode (default mode), all SCXI channels from one SCXI chassis are
multiplexed onto one onboard channel. Usually, this is channel 0 (
ob0
in the SCXI string), unless you are using more than one SCXI chassis;
in which case each additional chassis uses the next onboard channel
(i.e. Chassis 2 uses onboard channel 1, and so on).
‘ scx ’ represents the chassis number where x is replaced by the actual
number (e.g. sc1 ). The chassis are numbered starting with 1 and the
chassis number is assigned in the NI-DAQ configuration utility.
‘ mdy ’ represents the module number where y is replaced with the
actual number (e.g. md2 ). The modules are numbered 1 through n on
each SCXI chassis with module 1 being in the left-most slot of the
SCXI chassis and module n in the right-most slot.