Contents
SCXI-1141/1142/1143 User Manual vi ni.com
Chapter 4Theory of Operation
Power-Up State..............................................................................................................4-1
Digital Control Circuitry...............................................................................................4-3
Input Amplifiers............................................................................................................4-3
Correcting Gain and Offset Errors..................................................................4-4
Lowpass Filters..............................................................................................................4-5
Filter Theory...................................................................................................4-5
Performance of the SCXI-1141/1142/1143 Module Filters............................4-6
Magnitude Response.........................................................................4-6
Phase Response.................................................................................4-8
Setting the Cutoff Frequency............................................................4-11
Using the SCXI-1141/1142/1143 Module as an Antialiasing Filter............... 4-12
Using the External Clock Input.......................................................................4-14
DC-Correction Circuitry and Overload Recovery.......................................... 4-15
Filter Bypass Mode.........................................................................................4-16
Rear Connector Analog Outputs...................................................................................4-16
Multiplexed Mode (Recommended)...............................................................4-16
Parallel Mode..................................................................................................4-17
Chapter 5Using the SCXI-1141/1142/1143 Module
Developing Your Application in NI-DAQmx...............................................................5-1
Typical Program Flowchart............................................................................5-1
General Discussion of Typical Flowchart.......................................................5-3
Creating a Task Using DAQ Assistant or Programmatically........... 5-3
Adjusting Timing and Triggering.....................................................5-3
Configuring Channel Properties.......................................................5-4
Acquiring, Analyzing, and Presenting..............................................5-7
Completing the Application..............................................................5-7
Developing an Application Using LabVIEW.................................................5-7
Using a NI-DAQmx Channel Property Node in LabVIEW............. 5-9
Specifying Channel Strings in NI-DAQmx.................................................... 5-10
Text Based ADEs.............................................................................5-10
Programmable NI-DAQmx Properties............................................. 5-12
Calibration.....................................................................................................................5-13
External Calibration........................................................................................5-13
Appendix ASpecifications