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Lesson 1 introduction to real time

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Lesson 1 introduction to real time

  1. 1. Lesson 1 Introduction to Real TimeTOPICSA. What is Real-Time?B. RT HostC. RT Target ni.com/training
  2. 2. A. What is Real Time? Real Time Response: The ability to reliably and, without fail, respond to an event or perform an operation, within a guaranteed time period. ni.com/training
  3. 3. Real-Time TermsLoop Cycle Time • Execution time of one cycle of a loopJitter • Variation from the desired loop cycle timeDeterminism • Measure of jitter magnitudeLatency • Time required to respond to an event, or the time between input and output ni.com/training
  4. 4. Real-Time Terms (continued)Embedded • A computer system that is a component within a larger system. Embedded systems usually operate headlessly. ni.com/training
  5. 5. Maximum Jitter Jitter Range Desired Loop Time Maximum Jitter 1Loop Iteration 2 3 4 5 Loop Time (seconds) ni.com/training
  6. 6. Operating Systems • Processor time is shared between programs • Operating systems can preempt high priority VIs − Many programs run in the background—screen savers, disk utilities, virus software, and so on − It must service interrupts—keyboard, mouse, Ethernet, and so on • Cannot guarantee determinism—that is, it is a non-deterministic system ni.com/training
  7. 7. Real-Time Operating Systems• Ensure that high-priority tasks execute first• Do not require user input from peripheralsLabVIEW Real-Time Module executes VIs on the following:• Hardware targets running the Ardence Phar Lap Embedded Tool Suite (ETS)• Computers running Wind River VxWorks This course focuses on the ETS platform ni.com/training
  8. 8. Selecting an Operating SystemGeneral Real-Purpose Closed loop Data acquisition Time OS OS control Time-critical Offline analysis decisions Data presentation Extended run time Stand alone operation Increased reliability ni.com/training
  9. 9. Real-Time Development Tools Compiler Linker LabVIEW Real-TimeSoftware Debugger System Analysis Tools Execution Trace Tool RTOS LabVIEW Real-TimeHardware Microprocessor Target I/O Device ni.com/training
  10. 10. LabVIEW Real-Time System Using ETS Host Computer RT Target Develop Execute Download ni.com/training
  11. 11. Discussion Exercise 1-1: Project Specification Document Read and discuss the Project Specification document and determine if real time is necessary for this application.GOAL ni.com/training
  12. 12. B. Real-Time Host Host Computer ni.com/training
  13. 13. C. Real-Time Targets Desktop PCs Determinism for PCI systems NI RT PXI Embedded Controllers High speed, high channel density, I/O variety NI RT Compact FieldPoint Small footprint, harsh environments LabVIEW Real-Time NI Compact Vision System Compact and distributed machine vision NI CompactRIO Reconfigurable Embedded System ni.com/training
  14. 14. Real-Time Hardware Configuration Desktop PCs Determinism for PCI systems NI RT PXI Embedded Controllers High speed, high channel density, I/O variety NI RT Compact FieldPointHost-Target Small footprint, harsh environments NI RT Compact Vision System Compact and distributed machine vision NI CompactRIO Reconfigurable Embedded System ni.com/training
  15. 15. RT Target – Host-Target ConfigurationNI RT Series PXI Controller—Ideal for high-speed, high channel count acquisitionNI cRIO Series—Embedded system with real-time controller, reconfigurable FPGA chassis, and industrial I/O modulesNI RT Series Compact FieldPoint Controller—Ideal for distributed real-time I/O applicationsNI 1450 Series Compact Vision System— Acquires, processes, and displays images for IEEE1394 camerasDesktop PCs as RT Targets—Ideal for low cost implementation ni.com/training
  16. 16. RT Target – PXI Embedded Controller Processor PXI BackplaneConnect to host Memory DAQ Devices SCXI Modules ni.com/training
  17. 17. RT Target—cFP Controller Watchdog timer Removable CompactFlash memory (cFP-2x20 only) Onboard static memory Dedicated processor User-defined DIP switches and LEDs Serial port Backup power supply connection Ethernet port ni.com/training
  18. 18. Target Platform Comparison PXI cRIO cFP PC Loop Speed Best Better Good Best I/O Count High High High Low Rugged Better Best Best — Scalability Best Better Good Better Third-party RT HW Yes Yes No Yes Distributed Better Best Best Good ni.com/training
  19. 19. Summary – Matching Quiz1. Jitter A. How reliably a system responds to events or performs operations within a given time2. Determinism limit B. Time taken to execute one cycle of a loop3. Embedded C. Variation of loop cycle time from the4. Real time desired loop cycle time D. Computer system that is typically a5. Loop cycle component within a larger system time E. The ability to reliably, and without fail, respond to an event or perform an operation within a guaranteed time period ni.com/training

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