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National Instruments 653X How Much Current Can I Sink or Source?

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Appendix D Hardware Considerations

© National Instruments Corporation D-9 653X User Manual

There is no specific cutoff frequency at which termination becomes

necessary.

Note A purely resistive termination scheme is not recommended because of the current

drawn by the termination resistors. For example, a 90Ω terminating resistor works well to

dampen reflections, but sinks 27mA even at 2.4 V. The DIO-32HS is only rated to sink

24 mA.

Follow these signal-conditioning recommendations for optimum use:

•Separate 653Xdevice signal lines from high-current or high-voltage

lines. These lines are capable of inducing currents in or voltages on the

653Xdevice signal lines if they run in parallel paths at a close distance.

To reduce the magnetic coupling between lines, separate them by a

reasonable distance if they run in parallel, or run the lines at right

angles to each other.

•Do not run signal lines through conduits that also contain power lines.

How Much Current Can I Sink or Source?

Make sure the sink current does not exceed 24mA at 0.4 V to guarantee

that TTL low voltage specifications are met. The sink current is the amount

of current that flows into the 653Xdevice when it asserts a TTL low signal

(often denoted by Iout or Iol under Output Low Voltage specification).

Also, it is important to make sure the source current does not exceed

–24 mA at 2.4 V to guarantee TTL high voltage specifications. The source

current is the amount of current that flows out of the 653Xdevice when it

asserts a TTL high signal (often denoted by Iout or Ioh under output high

voltage specification).

Note Most National Instruments digital I/O products have similar source and sink

currents.

Note If you are using the DAQCard-6533 for PCMCIA, your PCMCIA socket may not

provide sufficient power to drive all outputs at 24mA.

Table D-2. Sink and Source Current for the 653X Devices

Sink Current Source Current

24mA at 0.4 V –24mA at 2.4 V

Contents

Main Page Important Information Warranty Copyright Trademarks WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS Compliance FCC/Canada Radio Frequency Interference Compliance* Determining FCC Class FCC/DOC Warnings Class A European Union - Compliance to EEC Directives Conventions Contents Chapter 1 Getting Started with Your 653X Chapter 2 Using Your 653X Chapter 3 Timing Diagrams Page Getting Started with Your 653X 653X Device Overview Control Lines What You Need to Get Started Choosing Your Programming Software National Instruments Application Software NI-DAQ Driver Software Installing Your Software Unpacking Your 653XDevice Installing Your 653XDevice Installing the PCI-DIO-32HS, PCI-6534, or PCI-7030/6533 Installing the PXI-6533, PXI-6534, or PXI-7030/6533 Installing the AT-DIO-32HS Installing the DAQCard-6533 for PCMCIA Configuring the 653X In Windows In Mac OS Using Your 653X Choosing the Correct Mode for Your Application Controlling and Monitoring Static Digital LinesUnstrobed I/O Configuring Digital Lines Standard Output Wired-OR Output Using Control Lines as Extra Unstrobed Data Lines Page Programming the Control/Timing Lines as Extra Unstrobed Data Lines Transferring Data Between Two DevicesHandshaking I/O Deciding the Width of Data to Transfer Deciding Data Transfer Direction Deciding Which Handshaking Protocol to Use Using the Burst Protocol Deciding the PCLK Signal Direction Selecting ACK/REQ Signal Polarity Choosing Whether or Not to Use a Programmable Delay Continuous Output Page Choosing the Startup Sequence Using an Initialization Order Controlling Line Polarities Chapter 2 Using Your 653X Figure 2-4. Programming Buffered Handshaking I/O in NI-DAQ National Instruments Corporation 2-13 653X User Manual Figure 2-5. Programming Unbuffered Handshaking I/O in NI-DAQ Figure 2-6. Programming Handshaking Input inLabVIEW/LabVIEW RT Figure 2-7. Programming Handshaking Output in LabVIEW/LabVIEW RT Generating and Receiving Digital Patterns and Waveform sPattern I/O Deciding the Width of Data to Transfer Deciding Transfer Direction Choosing an Internal or External REQ Source Deciding the REQ Polarity Deciding the Transfer Rate Deciding How to Start and Stop Data TransferTriggering Start Trigger Stop Trigger Start and Stop Trigger Pattern-Matching Trigger (Input Only) Page Continuous Output Monitoring Data Transfer Page Figure 2-13. Programming Pattern I/O (Continuous) in NI-DAQ Figure 2-14. Programming Pattern I/O in LabVIEW/LabVIEW RT Monitoring Line StateChange Detection Deciding the Width of Data to Acquire Deciding Which Lines You Want to Monitor Deciding How to Start and Stop Data TransferTriggering Start Trigger Stop Trigger Start and Stop Trigger Pattern-Matching Trigger Page Page Chapter 2 Using Your 653X 653X User Manual 2-32 ni.com Figure 2-20. Programming Change Detection (Continuous) in NI-DAQ Specify data mask here Figure 2-21. Programming Change Detection (Single Buffer) in NI-DAQ Specify data mask here Figure 2-22. Programming Change Detection for LabVIEW/LabVIEW RT Timing Diagrams Pattern I/O Timing Diagrams Internal REQ Signal Source External REQ Signal Source t t t t t Handshaking I/O Timing Diagrams Comparing the Different Handshaking Protocols Using the Burst Protocol Page Page t t t t t t t t t t t t t t t t t t t t t t t t Using Asynchronous Protocols Using the 8255-Emulation Protocol Page Figure 3-10. 8255 Emulation Input State Machine Page Figure 3-12. 8255 Emulation Output State Machine t t t t t t t t t Using the Level-ACK Protocol Figure 3-15. Level ACK Input State Machine t t t Page Figure 3-18. Level ACK Output State Machine t t t Using Protocols Based on Signal Edges Using the Trailing-Edge Protocol Figure 3-20. Trailing Edge Input Handshaking Sequence Figure 3-21. Trailing Edge Input State Machine t Figure 3-23. Trailing Edge Output Handshaking Sequence Figure 3-24. Trailing Edge Output State Machine t t t Using the Leading-Edge Protocol Figure 3-27. Leading Edge Input State Machine t t t Page Figure 3-30. Leading Edge Output State Machine X t t Using the Long-Pulse Protocol Figure 3-33. Long Pulse Input State Machine t t * Figure 3-36. Long Pulse Output State Machine t A Specifications Digital I/O Memory Page Power Requirement Power Available at I/O Connector Physical Environment Page B Using PXI with CompactPCI C Connecting Signals with Accessories Control Signals Appendix C Connecting Signals with Accessories 653X User Manual C-2 ni.com Making 68-Pin Signal Connections Caution Do not make connections that exceed any of the maximum input or output ratings Figure C-1. 653X I/O Connector 68-Pin Assignments Signal Descriptions Table C-3. Signal Descriptions Table C-3. Signal Descriptions (Continued) Making 50-Pin Signal Connections Figure C-2. 68-to-50-Pin Adapter Pin Assignments Use TableC-4 to find the accessories designed to connect to your 653Xdevice. Optional Equipment for Connecting Signals D Hardware Considerations Figure D-1. AT-DIO-32HS Block Diagram Block Diagrams Figure D-2. DAQCard-6533 for PCMCIA Block Diagram Figure D-3. PCI-DIO-32HS, PCI/PXI-7030/6533, and PXI-6533 Block Diagram Appendix D Hardware Considerations FPGA PCI I/O Channel SCARAB Memory 1 Figure D-4. PCI/PXI-6534 Block Diagram 653X User Manual D-4 ni.com Data Lines (32) Control Lines (8) RTSI/PXI Trigger Bus Power-On State Power Connections Selecting and Terminating Cables Using the Schottky-Diode Termination Scheme Page How Much Current Can I Sink or Source? RTSI and PXI Trigger Bus Interfaces Board, RTSI, and PXI Bus Clocks RTSI and PXI Bus Triggers E Optimizing Your Transfer Rates Determining the Maximum Transfer Rates Obtaining the Fastest Transfer Rates Interpreting Benchmark Results AT-DIO-32HS PCI-DIO-32HS PXI-6533 DAQCard-6533 for PCMCIA PCI-6534 PXI-6534 PCI-7030/6533 with LabVIEW RT PXI-6533 with LabVIEW RT Page F Technical Support Resources Web Support NI Developer Zone Customer Education System Integration Worldwide Support Glossary Numbers/Symbols A B C D F Page M P R S T U V Page Index Numbers A B C D E F G H Page I L M N O P R S Page T U V