National Instruments SCXI-1121 - Manual (Page 5)

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