Chapter 5 Using the SCXI-1125
SCXI-1125 User Manual 5-28 ni.com
C and Low-Level DAQ Functions
When using a C-based environment, several steps are needed to configure
the SCXI-1125 for multiplexed scanning. The following procedure outlines
the steps for programming with the low-level DAQ function calls:
1. Prepare the SCXI-1125 settings by either loading the original SCXI
configuration settings using SCXI_Load_Config, or by specifying
the gain and filter settings using SCXI_Set_Gain and
SCXI_Configure_Filter.
2. Use SCXI_SCAN_Setup to specify the module scan list, the start
channel of each module, and the number of channels to scan on each
module. SCXI_SCAN_Setup accepts an array of start channels and an
array of the number of channels to scan in each module. It is not
possible to repeat channels or use nonsequential channels using
SCXI_SCAN_Setup.
3. Next, use SCXI_MuxCtr_Setup to program the E Series DAQ device
with the correct number of channels multiplexed per scan. This
number must match the total number of channels programmed in
step 2.
You are now ready to acquire the channel data with the E Series DAQ
device. If you are using a multifunction E Series DAQ device, you can use
SCAN_OP to perform the scanning operation. After scanning, convert the
binary data to voltage data using SCXI_Scale. Refer to the NI-DAQ User
Manual for additional information on scanning with DAQ devices.
Using Software for Parallel Scanning
Performing scanning operations in parallel mode requires no special
channel strings or function calls for setting up channel sequencing as is
required in multiplexed mode. Scanning the SCXI-1125 channels on a
differentially configured DAQ device is done as if there were no
SCXI-1125 module connected. The only requirement is that you must
configure the module for parallel mode in MAX as described in Chapter 1,
About the SCXI-1125.
LabVIEW and Parallel Mode
In LabVIEW, the SCXI-1125 configuration settings are automatically
passed from MAX. LabVIEW can also set the SCXI-1125 configuration
parameter, operating mode, to parallel or multiplexed programmatically
by using the Set SCXI Information VI. In Measurement Studio, set the
operating mode using MAX as described in Chapter 1, About the
SCXI-1125.