Document Outline

• NI USB-621x User Manual
• Support
  • Worldwide Technical Support and Product Information
  • National Instruments Corporate Headquarters
  • Worldwide Offices
• Important Information
  • Warranty
  • Copyright
  • Trademarks
  • Patents
  • WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS
• Contents
• About This Manual
  • Conventions
  • Related Documentation
    • NI-DAQmx for Windows
    • LabVIEW
    • LabWindows™/CVI™
    • Measurement Studio
    • ANSI C without NI Application Software
    • .NET Languages without NI Application Software
    • Device Documentation and Specifications
    • Training Courses
    • Technical Support on the Web
• Chapter 1 Getting Started
  • Figure 1-1. USB-6210/6211
  • Figure 1-2. USB-6215/6218
  • Installing NI-DAQmx
  • Installing Other Software
  • Installing the Hardware
  • Device Pinouts
  • Device Specifications
  • Device Accessories
• Chapter 2 DAQ System Overview
  • Figure 2-1. Components of a Typical DAQ System
  • DAQ Hardware
    • Figure 2-2. USB-621x Block Diagram
    • DAQ-STC2
    • Calibration Circuitry
  • Signal Conditioning
    • Sensors and Transducers
  • Programming Devices in Software
• Chapter 3 Connector Information
  • I/O Connector Signal Descriptions
    • Table 3-1. I/O Connector Signals
  • +5 V Power
    • +5 V Power as an Output
    • +5 V Power as an Input
• Chapter 4 Analog Input
  • Figure 4-1. M Series Analog Input Circuitry
  • Analog Input Circuitry
  • Analog Input Range
    • Table 4-1. Input Ranges for NI 621x
  • Analog Input Ground-Reference Settings
    • Table 4-2. Analog Input Ground-Reference Settings
      • Figure 4-2. NI-PGIA
    • Table 4-3. Signals Routed to the NI-PGIA
    • Configuring AI Ground-Reference Settings in Software
      • Figure 4-3. Enabling Multimode Scanning in LabVIEW
  • Multichannel Scanning Considerations
    • Use Low Impedance Sources
    • Carefully Choose the Channel Scanning Order
      • Avoid Switching from a Large to a Small Input Range
      • Insert Grounded Channel between Signal Channels
      • Minimize Voltage Step between Adjacent Channels
    • Avoid Scanning Faster Than Necessary
      • Example 1
      • Example 2
  • Analog Input Data Acquisition Methods
    • Software-Timed Acquisitions
    • Hardware-Timed Acquisitions
      • Buffered
      • Non-Buffered
  • Analog Input Digital Triggering
  • Field Wiring Considerations
  • Analog Input Timing Signals
    • Figure 4-4. Analog Input Timing Options
    • Figure 4-5. Interval Sampling
    • Figure 4-6. Posttriggered Data Acquisition Example
    • Figure 4-7. Pretriggered Data Acquisition Example
    • AI Sample Clock Signal
      • Using an Internal Source
      • Using an External Source
      • Routing AI Sample Clock Signal to an Output Terminal
      • Other Timing Requirements
      • Figure 4-8. ai/SampleClock and ai/StartTrigger
    • AI Sample Clock Timebase Signal
    • AI Convert Clock Signal
      • Using an Internal Source
      • Using an External Source
      • Routing AI Convert Clock Signal to an Output Terminal
      • Using a Delay from Sample Clock to Convert Clock
      • Figure 4-9. ai/SampleClock and ai/ConvertClock
      • Other Timing Requirements
      • Figure 4-10. ai/SampleClock Too Fast
      • Figure 4-11. ai/ConvertClock Too Fast
      • Figure 4-12. ai/SampleClock and ai/ConvertClock Improperly Matched
      • Figure 4-13. ai/SampleClock and ai/ConvertClock Properly Matched
      • Figure 4-14. Single External Signal Driving ai/SampleClock and ai/ConvertClock Simultaneously
    • AI Convert Clock Timebase Signal
    • AI Hold Complete Event Signal
    • AI Start Trigger Signal
      • Using a Digital Source
      • Routing AI Start Trigger to an Output Terminal
    • AI Reference Trigger Signal
      • Figure 4-15. Reference Trigger Final Buffer
      • Using a Digital Source
      • Routing AI Reference Trigger Signal to an Output Terminal
    • AI Pause Trigger Signal
      • Using a Digital Source
  • Getting Started with AI Applications in Software
• Chapter 5 Connecting AI Signals on the USB-6210/6211 Devices
  • Table 5-1. Analog Input Configuration
  • Connecting Floating Signal Sources
    • What Are Floating Signal Sources?
    • When to Use Differential Connections with Floating Signal Sources
    • When to Use Referenced Single-Ended (RSE) Connections with Floating Signal Sources
    • When to Use Non-Referenced Single-Ended (NRSE) Connections with Floating Signal Sources
    • Using Differential Connections for Floating Signal Sources
      • Figure 5-1. Differential Connections for Floating Signal Sources without Bias Resistors
      • Figure 5-2. Differential Connections for Floating Signal Sources with Single Bias Resistor
      • Figure 5-3. Differential Connections for Floating Signal Sources with Balanced Bias Resistors
      • Figure 5-4. Differential Connections for AC Coupled Floating Sources with Balanced Bias Resistors
    • Using Non-Referenced Single-Ended (NRSE) Connections for Floating Signal Sources
      • Figure 5-5. NRSE Connections for Floating Signal Sources
    • Using Referenced Single-Ended (RSE) Connections for Floating Signal Sources
      • Figure 5-6. RSE Connections for Floating Signal Sources
  • Connecting Ground-Referenced Signal Sources
    • What Are Ground-Referenced Signal Sources?
    • When to Use Differential Connections with Ground-Referenced Signal Sources
    • When to Use Non-Referenced Single-Ended (NRSE) Connections with Ground-Referenced Signal Sources
    • When to Use Referenced Single-Ended (RSE) Connections with Ground-Referenced Signal Sources
    • Using Differential Connections for Ground-Referenced Signal Sources
      • Figure 5-7. Differential Connections for Ground-Referenced Signal Sources
    • Using Non-Referenced Single-Ended (NRSE) Connections for Ground-Referenced Signal Sources
      • Figure 5-8. Single-Ended Connections for Ground-Referenced Signal Sources (NRSE Configuration)
• Chapter 6 Connecting AI Signals on the USB-6215/6218 Devices
  • Differential Measurements
  • Differential Pairs
    • Table 6-1. I/O Connector Signals
      • Figure 6-1. Connecting a Device to a USB-6215/6218 Using Differential Connections
  • Referenced Single-Ended (RSE) Measurements
    • Figure 6-2. Connecting a Device to a USB-6215/6218 Using RSE Connections
  • Non-Referenced Single-Ended (NRSE) Measurements
    • Figure 6-3. Connecting a Device to a USB-6215/6218 Using NRSE Connections
• Chapter 7 Analog Output
  • Figure 7-1. M Series Analog Output Circuitry
  • Analog Output Circuitry
  • AO Range
  • Minimizing Glitches on the Output Signal
  • Analog Output Data Generation Methods
    • Software-Timed Generations
    • Hardware-Timed Generations
  • Analog Output Digital Triggering
  • Connecting Analog Output Signals
    • Figure 7-2. Analog Output Connections
  • Analog Output Timing Signals
    • Figure 7-3. Analog Output Timing Options
    • AO Start Trigger Signal
      • Using a Digital Source
      • Routing AO Start Trigger Signal to an Output Terminal
    • AO Pause Trigger Signal
      • Figure 7-4. ao/PauseTrigger with Other Signal Source
      • Using a Digital Source
    • AO Sample Clock Signal
      • Using an Internal Source
      • Using an External Source
      • Routing AO Sample Clock Signal to an Output Terminal
      • Other Timing Requirements
      • Figure 7-5. ao/SampleClock and ao/StartTrigger
    • AO Sample Clock Timebase Signal
  • Getting Started with AO Applications in Software
• Chapter 8 Digital I/O
  • Figure 8-1. M Series Digital I/O Circuitry
  • Static DIO
  • I/O Protection
  • Increasing Current Drive
  • Connecting Digital I/O Signals
    • Figure 8-2. Digital I/O Connections
  • Getting Started with DIO Applications in Software
• Chapter 9 Counters
  • Figure 9-1. M Series Counters
  • Counter Input Applications
    • Counting Edges
      • Single Point (On-Demand) Edge Counting
      • Figure 9-2. Single Point (On-Demand) Edge Counting
      • Figure 9-3. Single Point (On-Demand) Edge Counting with Pause Trigger
      • Buffered (Sample Clock) Edge Counting
      • Figure 9-4. Buffered (Sample Clock) Edge Counting
      • Non-Cumulative Buffered Edge Counting
      • Figure 9-5. Non-Cumulative Buffered Edge Counting
      • Controlling the Direction of Counting
    • Pulse-Width Measurement
      • Single Pulse-Width Measurement
      • Figure 9-6. Single Pulse-Width Measurement
      • Buffered Pulse-Width Measurement
      • Figure 9-7. Buffered Pulse-Width Measurement
    • Period Measurement
      • Single Period Measurement
      • Figure 9-8. Single Period Measurement
      • Buffered Period Measurement
      • Figure 9-9. Buffered Period Measurement
    • Table 9-1. Time N Descriptions
    • Semi-Period Measurement
      • Single Semi-Period Measurement
      • Buffered Semi-Period Measurement
      • Figure 9-10. Buffered Semi-Period Measurement
    • Frequency Measurement
      • Method 1-Measure Low Frequency with One Counter
      • Figure 9-11. Method 1
      • Method 1b-Measure Low Frequency with One Counter (Averaged)
      • Figure 9-12. Method 1b
      • Method 2-Measure High Frequency with Two Counters
      • Figure 9-13. Method 2
      • Method 3-Measure Large Range of Frequencies Using Two Counters
      • Figure 9-14. Method 3
      • Choosing a Method for Measuring Frequency
    • Table 9-2. Frequency Measurement Method 1
    • Table 9-3. Frequency Measurement Method Comparison
    • Position Measurement
      • Measurements Using Quadrature Encoders
      • Figure 9-15. X1 Encoding
      • Figure 9-16. X2 Encoding
      • Figure 9-17. X4 Encoding
      • Figure 9-18. Channel Z Reload with X4 Decoding
      • Measurements Using Two Pulse Encoders
      • Figure 9-19. Measurements Using Two Pulse Encoders
    • Two-Signal Edge-Separation Measurement
      • Single Two-Signal Edge-Separation Measurement
      • Figure 9-20. Single Two-Signal Edge-Separation Measurement
      • Buffered Two-Signal Edge-Separation Measurement
      • Figure 9-21. Buffered Two-Signal Edge-Separation Measurement
  • Counter Output Applications
    • Simple Pulse Generation
      • Single Pulse Generation
      • Figure 9-22. Single Pulse Generation
      • Single Pulse Generation with Start Trigger
      • Figure 9-23. Single Pulse Generation with Start Trigger
      • Retriggerable Single Pulse Generation
      • Figure 9-24. Retriggerable Single Pulse Generation
    • Pulse Train Generation
      • Continuous Pulse Train Generation
      • Figure 9-25. Continuous Pulse Train Generation
    • Frequency Generation
      • Using the Frequency Generator
      • Figure 9-26. Frequency Generator Block Diagram
      • Figure 9-27. Frequency Generator Output Waveform
    • Frequency Division
    • Pulse Generation for ETS
      • Figure 9-28. Pulse Generation for ETS
  • Counter Timing Signals
    • Counter n Source Signal
    • Table 9-4. Counter Applications and Counter n Source
      • Routing a Signal to Counter n Source
      • Routing Counter n Source to an Output Terminal
    • Counter n Gate Signal
      • Routing a Signal to Counter n Gate
      • Routing Counter n Gate to an Output Terminal
    • Counter n Aux Signal
      • Routing a Signal to Counter n Aux
    • Counter n A, Counter n B, and Counter n Z Signals
      • Routing Signals to A, B, and Z Counter Inputs
    • Counter n Up_Down Signal
    • Counter n HW Arm Signal
      • Routing Signals to Counter n HW Arm Input
    • Counter n Internal Output and Counter n TC Signals
      • Routing Counter n Internal Output to an Output Terminal
    • Frequency Output Signal
      • Routing Frequency Output to a Terminal
  • Default Counter/Timer Pinouts
    • Table 9-5. Default NI-DAQmx Counter/Timer Pins for USB-6210/6211/6215 Devices
    • Table 9-6. Default NI-DAQmx Counter/Timer Pins for USB-6218 Devices
  • Counter Triggering
    • Arm Start Trigger
    • Start Trigger
    • Pause Trigger
  • Other Counter Features
    • Sample Clock
      • Figure 9-29. Sample Clock Example
    • Table 9-7. Time N Descriptions
    • Cascading Counters
    • Counter Filters
    • Table 9-8. Filters
      • Figure 9-30. Filter Example
    • Prescaling
      • Figure 9-31. Prescaling
    • Duplicate Count Prevention
      • Example Application That Works Correctly (No Duplicate Counting)
      • Figure 9-32. Duplicate Count Prevention Example
      • Example Application That Works Incorrectly (Duplicate Counting)
      • Figure 9-33. Duplicate Count Example
      • Example Application That Prevents Duplicate Count
      • Figure 9-34. Duplicate Count Prevention Example
      • Enabling Duplicate Count Prevention in NI-DAQmx
• Chapter 10 PFI
  • Figure 10-1. NI 621x PFI Input Circuitry
  • Figure 10-2. NI 621x PFI Output Circuitry
  • Using PFI Terminals as Timing Input Signals
  • Exporting Timing Output Signals Using PFI Terminals
  • Using PFI Terminals as Static Digital I/Os
  • Connecting PFI Input Signals
    • Figure 10-3. PFI Input Signals Connections
  • PFI Filters
    • Table 10-1. Filters
      • Figure 10-4. Filter Example
  • I/O Protection
  • Programmable Power-Up States
• Chapter 11 Isolation and Digital Isolators
  • Table 11-1. Ground Symbols
    • Figure 11-1. General NI 621x Block Diagram
  • Digital Isolation
  • Benefits of an Isolated DAQ Device
  • Reducing Common-Mode Noise
    • Creating an AC Return Path
      • Isolated Systems
      • Non-Isolated Systems
• Chapter 12 Digital Routing and Clock Generation
  • 80 MHz Timebase
  • 20 MHz Timebase
  • 100 kHz Timebase
• Chapter 13 Bus Interface
  • USB Signal Streams
  • Data Transfer Methods
    • USB Signal Stream
    • Programmed I/O
    • Changing Data Transfer Methods
• Chapter 14 Triggering
  • Triggering with a Digital Source
    • Figure 14-1. Falling-Edge Trigger
• Appendix A Device-Specific Information
  • Figure A-1. USB-6210 Pinout
  • Table A-1. Default NI-DAQmx Counter/Timer Pins
  • Table A-2. PWR/ACT LED Status
    • Figure A-2. USB-6211/6215 Pinout
  • Table A-3. Default NI-DAQmx Counter/Timer Pins
  • Table A-4. PWR/ACT LED Status
    • Figure A-3. USB 6218 Pinout
  • Table A-5. Default NI-DAQmx Counter/Timer Pins
  • Table A-6. PWR/ACT LED Status
• Appendix B Troubleshooting
  • Figure B-1. ai/SampleClock and ai/ConvertClock
• Appendix C Technical Support and Professional Services
• Glossary
  • A
  • B-C
  • D
  • E
  • F
  • G-I
  • K
  • L-M
  • N
  • O-P
  • Q-S
  • T
  • U-V
  • W
• Index
  • Symbols
  • Numerics
  • A
  • B-C
  • D
  • E
  • F-I
  • K-N
  • O-R
  • S
  • T-U
  • W-X
• Device Pinouts
  • Figure A-1. USB-6210 Pinout
  • Figure A-2. USB-6211/6215 Pinout
  • Figure A-3. USB 6218 Pinout