National Instruments SCXI-1120 - Manual (Page 5)

Contents
SCXI-1120 User Manual vi © National Instruments Corporation
Digital I/O Signal Connections .............................................................. 2-26
Timing Requirements and Communication Protocol............................. 2-28
Timing Signal............................................................................. 2-28
Communication Signals ......................................................................... 2-28
Chapter 3
Theory of Operation
.......................................................................................................... 3-1
Functional Overview ...................................................................................................... 3-1
SCXIbus Connector ........................................................................................... 3-2
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
Calibration.......................................................................................................... 3-10
Calibration Equipment Requirements .................................................... 3-10
Offset Null Adjust .................................................................................. 3-11
Analog Output Circuitry ........................................................................ 3-12
Scanning Modes ............................................................................................................. 3-13
Single-Module Parallel Scanning....................................................................... 3-14
Multiplexed Scanning ........................................................................................ 3-14
Single-Module Multiplexed Scanning ................................................... 3-14
Single-Module Multiplexed Scanning (Direct).......................... 3-14
Single-Module Multiplexed Scanning (Indirect) ....................... 3-15
Multiple-Module Multiplexed Scanning................................................ 3-15
Multiple-Chassis Scanning .................................................................... 3-16
Chapter 4
Register Descriptions
......................................................................................................... 4-1
Register Description....................................................................................................... 4-1
Register Description Format .............................................................................. 4-1
SCXI-1120 Registers ......................................................................................... 4-1
Module ID Register................................................................................ 4-2
Configuration Register ........................................................................... 4-3
Slot 0 Register Descriptions............................................................................... 4-5
Slot-Select Register ................................................................................ 4-6
Hardscan Control Register (HSCR) ....................................................... 4-7
FIFO Register......................................................................................... 4-8
Chapter 5
Programming
........................................................................................................................ 5-1
Programming Considerations......................................................................................... 5-1
Notation.............................................................................................................. 5-1
Register Writes................................................................................................... 5-1
Register Selection and Write Procedure ................................................ 5-2
Initialization ........................................................................................... 5-3