Contents
SCXI-1503 User Manual vi ni.com
Chapter 4Theory 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 5Using 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