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1 Lesson 9 Data Acquisition and Waveforms TOPICS Plug-in DAQ devices Data Acquisition in LabVIEW Analog Input Data Logging Analog Output Counters Digital.

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Presentation on theme: "1 Lesson 9 Data Acquisition and Waveforms TOPICS Plug-in DAQ devices Data Acquisition in LabVIEW Analog Input Data Logging Analog Output Counters Digital."— Presentation transcript:

1 1 Lesson 9 Data Acquisition and Waveforms TOPICS Plug-in DAQ devices Data Acquisition in LabVIEW Analog Input Data Logging Analog Output Counters Digital I/O

2 2 Overview and Configuration Fundamental task of a DAQ system is to measure or generate real-world physical signals DAQ system consists of: Transducers Signal Conditioning Plug-in DAQ device Driver Software

3 3 Measurement Software Framework NI-DAQ contains: Traditional NI-DAQ NI-DAQmx

4 4 DAQ Hardware Configuration Measurement & Automation Explorer (MAX)

5 5 Channels and Tasks Signals ai 0 ai 1 ai 2 Sine Wave 1 Sine Wave 2 Sine Wave 3 Channel names Tasks Timing and Triggering

6 The DAQ Signal Accessory

7 7 NI-DAQmx versus Traditional NI-DAQ FeatureNI-DAQmxTraditional NI-DAQ Test Panels DAQ Assistant with code generation no On-line diagnostics Scaling to voltage and physical units 50 kS/s with single point I/O Measurement multithreading Instant calibration Automatic selection of optimal gains Guaranteed lossless data 650 Alliance members Integration with LabVIEW Developer Exchange discussion forum Compatible with Legacy ISA Boardsno Accuracy Performance Productivity Quality Best Good Fair Compatibility

8 8 Data Acquisition in LabVIEW Traditional NI-DAQ Specific VIs for performing: Analog Input Analog Output Digital I/O Counter operations NI-DAQmx Next generation driver: VIs for performing a task One set of VIs for all measurement types

9 9 NI-DAQmx Data Acquisition Single set of VIs used to perform analog I/O, digital I/O, and counter operations DAQ Assistant Express VI Quickly and easily program the DAQ device Creates a local task Most applications can use the DAQ Assistant Express VI

10 10 NI-DAQmx Data Acquisition Task Types Measurement type can be: Analog Input Analog Output Counter Input Counter Output Digital I/O

11 11 Analog Input Analog Input task is specific to the measurement

12 12 Analog Input Task Timing and Triggering Configures the number of samples and sample rate for the task Configures the start and reference triggers for the task

13 13 Data Logging It is often necessary to permanently store data that is acquired from the DAQ device LabVIEW includes the ability to read and write a LabVIEW Measurement File LabVIEW Measurement File is an ASCII text file

14 14 Analog Output Analog Output task is specific to the generation type

15 15 Analog Output Task Timing and Triggering Configures the number of samples and sample rate for the task Configures the start and reference triggers for the task

16 16 Counters A counter is a digital timing device Typical uses of a counter: Event counting Frequency measurement Period measurement Position measurement Pulse generation Gate Source Output Count Register Count register – Stores the current count of the counter Source – Input that causes the counter to increment each time it toggles Gate – Input that is used to enable or disable the function of the counter Output – Signal that generates pulses or a series of pulses

17 17 Digital Input and Output Digital I/O can read from or write to a line or an entire digital port A digital port is a collection of digital lines

18 18 Summary MAX is the primary configuration and testing utility that is available for the DAQ device. The DAQ Assistant is used to configure the DAQ device and perform data acquisition. Most application can use the DAQ Assistant. For applications that require advanced timing and synchronization use the VIs that come with NI-DAQmx. The DAQ Assistant can perform Analog Input, Analog Output, Digital I/O, and Counter operations.

19 19 Lesson 10 Instrument Control TOPICS Instrument Control Overview GPIB Communication and Configuration Instrument I/O Assistant Virtual Instrument Software Architecture (VISA) Instrument Drivers Serial Port Communication Waveform Transfers

20 20 Instrument Control Overview Control any instrument if you know the following: –Type of connector on the instrumentType of cables needed –Electrical properties involvedCommunication protocols used –Software drivers available Instruments Computer

21 GPIB Communication GPIB Instruments GPIB Cable GPIB Interface

22 22 Standards Introduction HP designs HP-IB (Hewlett Packard Interface Bus) HP-IB becomes IEEE 488 IEEE adopted IEEE 488 becomes IEEE SCPI (Standard Commands for Programmable Instruments) added to IEEE IEEE revised HS488 proposed 1999 HS488 approved

23 23 GPIB Hardware Specifications Max cable length between devices = 4 m (2 m average) Max cable length = 20 m Max number of devices = 15 (2/3 powered on) DIO5 DIO6 DIO7 DIO8 REN GND (TW PAIR W/DAV) GND (TW PAIR W/NRFD) GND (TW PAIR W/NDAC) GND (TW PAIR W/IFC) GND (TW PAIR W/SRQ) GND (TW PAIR W/ATN) SIGNAL GROUND DIO1 DIO2 DIO3 DIO4 EOI DAV NRFD NDAC IFC SRQ ATN SHIELD

24 GPIB Software Architecture Windows Driver Software (*.DLL) Instrument Driver VIs NI-VISA LabVIEW Diagnostics Tools: GPIB Diagnostic Tool NI-Spy Configuration Tools: Measurement & Automation Explorer Interface Board (GPIB, PXI, VXI, computer based, etc.)

25 25 Configuring GPIB Board and Instruments Measurement & Automation Explorer (MAX)

26 26 What is the Instrument I/O Assistant? Accessed through a LabVIEW Express VI Sets up device communication and data parsing step by step through a configuration interface

27 27 Communicating with an Instrument

28 28 Virtual Instrument Software Architecture Platform independent VISA is the backbone of the IVI and Plug & Play Instrument Drivers Interface independent Must know SCPI command set to program directly with VISA GPIBVXISerialPXI VISA

29 29 VISA Terminology Resource Instrument, Serial Port, or Parallel Port Session Connection to a Resource Instrument Descriptor Resource location –Format: Interface Type::Address::INSTR –Examples:

30 30 Instrument Descriptor Syntax Resource Name contains interface info VISA Aliases also work InterfaceResource Name Grammar Serial ASRL[board][::INSTR] GPIB GPIB[board]::primary address[::INSTR] VXI VXI[board]::VXI logical address[::INSTR] GPIB-VXI GPIB-VXI[board][::GPIB-VXI primary address]::VXI logical address[::INSTR]

31 31 VISA Resource Name Exact name and location of the instrument Use the VISA Resource Name control You can specify the full resource name of the VISA Alias

32 32 Instrument Drivers More than 1200 LabVIEW Instrument drivers Programming simplified to high-level API

33 33 Installing and Finding Instrument Drivers Drivers available at Install the instrument driver VI Library into LabVIEW 7.0\instr.lib directory Access drivers from Functions»Input»Instrument Drivers subpalette

34 34 IDNET - Instrument Driver Network Learn about drivers Get help with developing drivers Submit your driver to the network Download drivers

35 35 Instrument Driver Model

36 36 Initialize Configure Action/Status Data Utility Close Instrument Driver VIs

37 37 Instrument Driver Inputs and Outputs Instrument Descriptor VISA Sessions -A connection or link to a specific instrument -Created after instrument is initialized -Used throughout VI whenever you communicate with that specific instrument Error cluster HP34401A

38 38 Putting It All Together Initialize instrument Do operation(s) Close instrument Check error status

39 39 Serial Communication Popular means of communication between computer and peripheral device Data sent one bit at a time across the cable Used for low transfer rates or long distances Only a cable is needed since most computers have at least one available serial port RS-232 Instrument RS-232 Cable PC Serial Port

40 40 Serial Hardware Connection RS-232 –DCE or DTE configurations –9-pin or 25-pin RS-422 –DCE or DTE –8-pin RS-485 –Multidrop PinDTEDCE 1 DCDInputOutput 2 RxD I O 3 TxD O I 4 DTR O I 5 Com DSR I O 7 RTS O I 8 CTS I O 9 RI I O

41 41 Serial Communication Terminology Baud rate – bits per second Data bits – inverted logic and LSB first Parity – optional error-checking bit Stop bits – 1, 1.5, or 2 inverted bits at data end Flow control – hardware and software handshaking options

42 42 Using the Instrument I/O Assistant with Serial Select COMX as the instrument address Use the I/O Assistant as done with GPIB

43 43 Summary LabVIEW can communicate with any instrument that connects to your computer if you know the interface type Use the Measurement & Automation Explorer (MAX) to detect, configure, and test your GPIB interface and instruments Use the Instrument I/O Assistant for easy and fast GPIB and serial programming. An instrument driver eliminates the need for your to have detailed knowledge of the specific strings used by an instrument Instrument Library – more than 2000 instruments supported Instrument driver VIs share a common hierarchy and come with an example to help you get started

44 44 Lesson 11 VI Customization TOPICS Configuring Appearance of Front Panel SubVI Front Panels Keyboard Shortcuts VI Properties Customizing Palettes

45 45 Customizing VI Properties Access VI Properties by right-clicking the icon pane or selecting it from the File menu Affects every instance of that VI in all applications

46 46 Window Appearance Only affects VI panel while VI is running

47 47 Window Size Set minimum and current panel size Adjust size of panel relative to the monitor Scale objects on panel as window resizes

48 48 Creating Pop-Up Panels – Every Instance Use Top-Level Application Window or Dialog appearance types Create custom window appearance

49 49 Creating Pop-Up Panels – Single Instance Access SubVI Node Setup by right-clicking on subVI icon on calling VIs diagram

50 50 Key Navigation Assigns keyboard strokes to front panel controls

51 51 Preventing Editing of a VI Opens, runs, and closes LabVIEW without user intervention Remove menus, Abort button, etc… Save with Options

52 52 Summary Use VI Properties to set VI execution, window, and documentation options Use SubVI Node Setup to set execution options for a single instance of a subVI Use the Key Navigation option to assign front panel controls to a keyboard key combination Use the Save with Options from the file menu to make backups of your VIs You can often edit VIs by aborting them from the diagram of another VI

53 53 Technical Support Resources Award-Winning Website Drivers & Updates Product Manuals KnowledgeBases Example Code Tutorials Application Notes Discussion Forums

54 54 Info-LabVIEW Listserve User-sponsored Internet mailing list Send subscription messages to the Info-LabVIEW list processor Send other administrative messages to the Info-LabVIEW list maintainer at Post a message to subscribers at

55 55 LabVIEW Publications LabVIEW Technical Resource quarterly newsletter by LTR Publishing LabVIEW Graphical Programming and LabVIEW Power Programming by Gary W. Johnson, McGraw-Hill LabVIEW for Everyone by Lisa K. Wells and Jeffrey Travis, Prentice-Hall LabVIEW Signal Processing by Mahesh Chugani, Abhay Samant, and Michael Cerna, Prentice-Hall LabVIEW Applications and Solutions by Rahman Jamal and Herbert Pichlik, Prentice-Hall

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