National Instruments SCXI-1121 Chapter 3 Theory of Operation, Chapter 4 Register Descriptions, Chapter 5 Programming

Contents
SCXI-1121 User Manual vi www.natinst.com
Chapter 3
Theory of Operation
Functional Overview.....................................................................................................3-1
SCXIbus Connector........................................................................................3-3
SCXIbus Connector Signal Descriptions........................................................3-4
Digital Interface.............................................................................................................3-6
Digital Control Circuitry...............................................................................................3-7
Analog and Timing Circuitry........................................................................................3-8
Analog Input Channels....................................................................................3-8
Excitation Output Channels............................................................................3-11
Calibration.......................................................................................................3-11
Calibration Equipment Requirements .............................................. 3-11
Offset Null Adjust............................................................................ 3-12
Excitation Adjust..............................................................................3-13
Analog Output Circuitry.................................................................................3-15
Scanning Modes............................................................................................................3-17
Single-Module Parallel Scanning....................................................................3-17
Multiplexed Scanning.....................................................................................3-17
Single-Module Multiplexed Scanning..............................................3-18
Multiple-Module Multiplexed Scanning.......................................... 3-19
Multiple-Chassis Scanning...............................................................3-20
Chapter 4
Register Descriptions
Register Description......................................................................................................4-1
Register Description Format...........................................................................4-1
SCXI-1121 Registers......................................................................................4-1
Slot 0 Register Descriptions............................................................................4-5
Chapter 5
Programming
Programming Considerations........................................................................................5-1
Notation...........................................................................................................5-1
Register Writes................................................................................................5-2
Register Selection and Write Procedure...........................................5-2
Initialization......................................................................................5-3
Single-Channel Measurements....................................................................... 5-4
Direct Measurements........................................................................5-4
Indirect Measurements..................................................................... 5-5
Scanning Measurements.................................................................................5-7
1. Data Acquisition Board Setup Programming............................... 5-7