Network Card User Manual
Table Of Contents
- SCXI-1121 User Manual
- Support
- Important Information
- Contents
- About This Manual
- Chapter 1 Introduction
- Chapter 2 Configuration and Installation
- Chapter 3 Theory of Operation
- Chapter 4 Register Descriptions
- Chapter 5 Programming
- Appendix A Specifications
- Appendix B Rear Signal Connector
- Appendix C SCXIbus Connector
- Appendix D SCXI-1121 Front Connector
- Appendix E SCXI-1121 Cabling
- Appendix F Revision A and B Photo and Parts Locator Diagrams
- Appendix G Technical Support Resources
- Glossary
- Index
- Figures
- Figure 2-1. SCXI-1121 General Parts Locator Diagram
- Figure 2-2. SCXI-1121 Detailed Parts Locator Diagram
- Figure 2-3. SCXI-1121 Front Connector Pin Assignment
- Figure 2-4. Ground-Referenced Signal Connection with High Common-Mode Voltage
- Figure 2-5. Floating Signal Connection Referenced to Chassis Ground for Better Signal-to-Noise Ratio
- Figure 2-6. Floating AC-Coupled Signal Connection
- Figure 2-7. AC-Coupled Signal Connection with High Common-Mode Voltage
- Figure 2-8. Assembling and Mounting the SCXI-1330 Connector-and-Shell Assembly
- Figure 2-9. Nulling Circuit
- Figure 2-10. Shunt Circuit
- Figure 2-11. SCXI-1320 Parts Locator Diagram
- Figure 2-12. SCXI-1328 Parts Locator Diagram
- Figure 2-13. SCXI-1321 Parts Locator Diagram
- Figure 2-14. SCXI-1121 Rear Signal Connector Pin Assignment
- Figure 2-15. SCANCLK Timing Requirements
- Figure 2-16. Slot-Select Timing Diagram
- Figure 2-17. Serial Data Timing Diagram
- Figure 2-18. Configuration Register Write Timing Diagram
- Figure 2-19. SCXI-1121 Module ID Register Timing Diagram
- Figure 3-1. SCXI-1121 Block Diagram
- Figure 3-2. SCXIbus Connector Pin Assignment
- Figure 3-3. Digital Interface Circuitry Block Diagram
- Figure 3-4. SCXI-1121 Digital Control
- Figure 3-5. Analog Input Block Diagram
- Figure 3-6. Analog Output Circuitry
- Figure 3-7. Single-Module Parallel Scanning
- Figure 3-8. Single-Module Multiplexed Scanning (Direct)
- Figure 3-9. Single-Module Multiplexed Scanning (Indirect)
- Figure 3-10. Multiple-Module Multiplexed Scanning
- Figure 3-11. Multiple-Chassis Scanning
- Figure B-1. SCXI-1121 Rear Signal Connector Pin Assignment
- Figure C-1. SCXIbus Connector Pin Assignment
- Figure D-1. SCXI-1121 Front Connector Pin Assignment
- Figure E-1. SCXI-1340 Installation
- Figure E-2. SCXI-1180 Rear Connections
- Figure E-3. SCXI-1180 Front Panel Installation
- Figure E-4. Cover Removal
- Figure F-1. Revision A and B SCXI-1121 Signal Conditioning Module
- Figure F-2. Revision A and B SCXI-1121 General Parts Locator Diagram
- Figure F-3. Revision A and B SCXI-1121 Detailed Parts Locator Diagram
- Tables
- Table 2-1. Digital Signal Connections, Jumper Settings
- Table 2-2. Jumper W33 Settings
- Table 2-3. Gain Jumper Allocation
- Table 2-4. Gain Jumper Positions
- Table 2-5. Filter Jumper Allocation
- Table 2-6. Voltage and Current Mode Excitation Jumper Setup
- Table 2-7. Maximum Load per Excitation Channel
- Table 2-8. Excitation Level Jumper Selection
- Table 2-9. Completion Network Jumpers
- Table 2-10. Trimmer Potentiometer and Corresponding Channel
- Table 2-11. Nulling Resistors and Corresponding Channel
- Table 2-12. Jumper Settings of the Nulling Circuits
- Table 2-13. Jumper Settings on the SCXI-1320 Terminal Block
- Table 2-14. Jumper Settings on the SCXI-1328 Terminal Block
- Table 2-15. Jumper Settings on the SCXI-1321 Terminal Block
- Table 2-16. SCXIbus to SCXI-1121 Rear Signal Connector to Data Acquisition Board Pin Equivalences
- Table 3-1. SCXIbus Equivalents for the Rear Signal Connector
- Table 3-2. Calibration Potentiometer Reference Designators
- Table 5-1. SCXI-1121 Rear Signal Connector Pin Equivalences
- Table E-1. SCXI-1121 and MIO-16 Pinout Equivalences
- Table E-2. SCXI-1341 and SCXI-1344 Pin Translations
- Table E-3. SCXI-1342 Pin Translations
- Table E-4. SCXI-1343 Pin Connections
Chapter 3 Theory of Operation
© National Instruments Corporation 3-11 SCXI-1121 User Manual
After isolation, further filtering is available to increase the noise immunity
of the amplifier channel. It is important to note that the overall amplifier
bandwidth is determined by both filtering stages, so to achieve the required
bandwidth, both filtering sections should be set the same, as indicated in
Chapter 2, Configuration and Installation.
Excitation Output Channels
In addition to the four input channels, the SCXI-1121 contains four fully
isolated excitation channels, each corresponding to an input channel. For
instance, input channel 0 corresponds to excitation channel 0. Each
excitation channel consists of a voltage/current source with overvoltage
protection and current limiting. Two levels of excitation are available for
each mode of operation. In the voltage mode you can set the level to
3.333V or 10 V in the current mode you can set the level to 150 µA or
450µA. You can choose one configuration out of the four available. To
configure the excitation channels refer to Chapter 2, Configuration and
Installation. The excitation channels are isolated from each other and are
independently configurable for voltage or current excitation.
Calibration
Calibration Equipment Requirements
For best measurement results, calibrate the SCXI-1121 so that its offset is
adjusted to 0 ± 3 mV RTO and 0 ± 6 µV RTI and its excitation output is
adjusted to ±0.04%. According to standard practice, the equipment used to
calibrate the SCXI-1121 should be 10 times as accurate as the SCXI-1121,
that is, have 0.004% rated accuracy. Practically speaking, calibration
equipment with four times the accuracy of the item under calibration is
generally considered acceptable. Four times the SCXI-1121 accuracy is
0.016%. To calibrate the SCXI-1121 you need the following equipment:
• For the excitation channels, you need a voltmeter with the following
specifications:
– Accuracy:±0.004% standard
±0.016% sufficient
– Range: 0 to +5 V for 3.333 V and greater than +10 V for 10 V
– Resolution:5 1/2 digits