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Contents
SCXI-1503 User Manual vi ni.com
Chapter 4
Theory of Operation
Rear Signal Connector, SCXIbus Connector, and SCXIbus Interface.......................... 4-3
Digital Control Circuitry ............................................................................................... 4-3
Analog Circuitry............................................................................................................4-3
Analog Input Channels.................................................................................... 4-3
Operation of the Current Sources.................................................................................. 4-4
Theory of Multiplexed Operation.................................................................................. 4-4
Measuring Temperature with Resistive Transducers .................................................... 4-5
RTDs ............................................................................................................... 4-5
RTD Measurement Errors ................................................................ 4-6
The Relationship Between Resistance and Temperature in RTDs... 4-6
Thermistors ..................................................................................................... 4-10
Thermistor Measurement Circuits.................................................... 4-11
Resistance/Temperature Characteristic of Thermistors.................... 4-12
Chapter 5
Using the SCXI-1503
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.............................................................. 5-8
Developing an Application Using LabVIEW ................................................. 5-8
Using a NI-DAQmx Channel Property Node in LabVIEW............. 5-10
Specifying Channel Strings in NI-DAQmx .................................................... 5-11
Text Based ADEs .............................................................................5-11
Programmable NI-DAQmx Properties ............................................. 5-13
Calibration.....................................................................................................................5-13
Internal/Self-Calibration ................................................................................. 5-13
External Calibration ........................................................................................ 5-13