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Chapter 4 Theory of Operation

SCXI-1120/D User Manual 4-6 www.natinst.com

Analog Input Channels

Figure 4-4 shows the analog input block diagram.

Figure 4-4.

Analog Input Block Diagram

LPF

Input Channel 0

Input Channel 1

Input Channel 2

Input Channel 3

Input Channel 4

Input Channel 5

Input Channel 6

Input Channel 7

To Output

Stage

To Output

Stage

To Output

Stage

To Output

Stage

To Output

Stage

To Output

Stage

To Output

Stage

To Output

Stage

Front Connector

MTEMP

DTEMP

SCXI-1120D Only

511 kΩ

SCXI-1120D Only

511 kΩ

SCXI-1120D Only

511 kΩ

SCXI-1120D Only

511 kΩ

SCXI-1120D Only

511 kΩ

SCXI-1120D Only

511 kΩ

SCXI-1120D Only

511 kΩ

SCXI-1120D Only

511 kΩ

Table of Contents4
About this Manual7
Conventions7
National Instruments Documentation8
About the SCXI-1120/D9
Introduction9
What You Need to Get Started10
National Instruments Application Software11
Software Programming Choices11
Unpacking11
NI-DAQ Driver Software12
Figure 1-1. the Relationship between the Programming Environment13
Optional Equipment13
Configuration and Installation14
Module Configuration14
Figure 2-1. SCXI-1120/D Parts Locator Diagram15
Digital Signal Connections17
Figure 2-2. Removing the SCXI Module Cover17
Using Jumpers W42 and W4318
Using Jumper W44 on Revision C of the SCXI-1120 and All Revisions of the SCXI-1120D19
Using Jumper W44 on Revisions a and B of the SCXI-112019
Table 2-1. Digital Signal Connections, Jumper Settings20
Analog Configuration21
Grounding, Shielding, and Reference-Mode Selection21
Table 2-2. Jumper W46 Settings22
Direct Temperature Connection23
Gain Jumpers for the SCXI-1120/D23
Table 2-3. Jumper W41 Settings23
Table 2-4. Gain Jumper Allocation23
Table 2-5. Gain Jumper Positions24
SCXI-1120 Filter Jumpers25
Table 2-6. SCXI-1120 Filter Jumper Allocation25
SCXI-1120D Filter Jumpers26
Table 2-7. SCXI-1120D Filter Jumper Allocation26
Hardware Installation27
Signal Connections28
Figure 3-1. SCXI-1120/D Front Connector Pin Assignments30
SCXI-1120/D Front Connector30
Front Connector Signal Descriptions31
Table 3-1. SCXI-1120/D Front Connector Signal Descriptions31
Analog Input Channels32
Figure 3-2. Ground-Referenced Signal Connection for the SCXI-1120/D with High Common-Mode Voltage32
Figure 3-3. Floating Signal Connection for the SCXI-1120/D Referenced to32
Floating AC-Coupled Signal Connection for the SCXI-112033
High Common-Mode Voltage33
Floating AC-Coupled Signal Connection for the SCXI-1120D34
High Common Mode Voltage34
Temperature Sensor Connection34
SCXI-1120/D Rear Connector35
SCXI-1120/D Rear Signal Connector Pin Assignments35
Rear Connector Signal Descriptions36
Table 3-2. Rear Connector Signal Descriptions36
Analog Output Signal Connections37
Table 3-3. Scxibus to SCXI-1120/D Rear Connector to DAQ Device Pin Equivalencies38
Functional Overview39
Theory of Operation39
Power-Up State40
Digital Interface Circuitry Block Diagram41
Scxibus Connector and Digital Interface41
Digital Control Circuitry42
Analog and Timing Circuitry43
Analog Input Block Diagram44
Analog Input Channels44
Analog Output Circuitry47
Calibration50
Calibration Equipment Requirements50
Offset Null Adjust50
Table 5-1. Calibration Potentiometers Reference Designators51
Appendix A Specifications52
- Table A-1. Input Signal Range56
- Table A-2. System Noise RTI (0.1 Hz to 50 Khz57
- Table A-3. Switching Supply Noise (Approximately at 100 Khz58
- Technical Support Resources60
- Glossary62
- Index69

Brand	National Instruments
Model	776570-00
Category	Control Unit
Language	English

National Instruments 776570-00 User Manual

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