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Department of Electrical and Computer Engineering

LabVIEW VI for Interfacing with Tektronix MSO4000 Oscilloscopes. Project Overview

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Department of Electrical and Computer Engineering

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  1. LabVIEW VI for Interfacing with Tektronix MSO4000 Oscilloscopes Project Overview The Tektronix MSO4000 series of oscilloscopes are mixed-signal oscilloscopes that contain both digital and analog channels. A previously developed custom step in National Instruments SignalExpress™ can be used to remotely control the analog channels of the oscilloscopes, but there is currently no means to remotely control the digital channels and buses. Our project is [was] to design and implement a LabVIEW Virtual Instrument that will allow a user to remotely configure and control the oscilloscope as well as acquire, analyze, and document measurements from the digital channels and bus waveforms. We designed a virtual instrument that will allow a user to remotely operate a Tektronix MSO4000 series oscilloscope using National Instruments LabVIEW. The purpose of this VI is to allow a person to control the oscilloscope by manipulating the controls in the user interface of this VI, rather than manipulating the controls that are on the front panel of the oscilloscope itself. Manipulating a control in LabVIEW should have the same effect on the oscilloscope as manipulating the equivalent control on the front panel of the oscilloscope. The user will be able to remotely control the digital channels, the buses, and the triggering features from LabVIEW. The interface allows the user to configure the digital buses and channels and adjust the trigger settings. It will also provide the user with control of other features, like enabling automatic measurements. The VI will also display an image of the waveform in LabVIEW and allow the user to acquire and save measurement data from the oscilloscope. We implemented our solution with a collection of individual virtual instruments, which are then packaged in a top-level master VI. The top level VI plots the waveform data on the graph while simultaneously governing execution all of the constituent VIs that are responsible for the configuration of the various feature groups of the oscilloscope. The configuration Vis are presented in a tabbed layout that allows the user to quickly and seamlessly switch between them, while never having to leave the waveform display - thus ensuring a smooth and seamless workflow. [A different configuration VI is selected by clicking on the appropriate tab of the top level VI. ] National Instruments LabVIEW is a powerful graphical programming environment for developing sophisticated measurement, test, and control systems. It is especially well-suited for rapid development of user-friendly interfaces capable of controlling complex hardware of all kinds. In LabVIEW, applications called Virtual Instruments (VIs), and they are constructed by wiring together different graphical icons instead of writing lines of text. Each graphical icon is a functional block ranging from simple arithmetic and boolean logic operators to GPIB and VISA hardware communications, control, and data transfer. LabVIEW allows the developer to quickly lay out a visually appealing and user-friendly front panel interface, the elements of which can then be connected to VI applets on the Block Diagram (the ‘source code’). By thinking hierchially and planning ahead, portions of code which will be repeatedly useful can be saved as VIs themselves and incorporated into future programs. The Tektronix MSO4000 series mixed-signal oscilloscope is capable of analyzing both analog and digital signals, and includes specialized high-level functionality for analyzing and interpreting multichannel digital and bus waveforms. Sixteen digital inputs combine with the four analog inputs for a total of twenty channels. These inputs can be viewed and measured as individual digital waveforms or can be fully decoded using automated serial and parallel bus analysis with a selection of nine different communication bus protocols, including Parallel, I2C, SPI, LIN, CAN, RS-232, FlexRay, USB, and Audio. • Digital Channel VI • The MSO4000 series includes a set of dedicated digital input channels, much like a logic analyzer. This VI allows the user to configure and control the 16 digital channels, D0-D15. • The user is able to: • Turn each of the 16 digital channels on or off, either individually or in groups of eight • Adjust the height of the digital channel waveforms • Turn the MagniVu feature on or off • Adjust the vertical positions of the digital channel waveforms • Edit the text labels of each digital channel • Set the logic threshold voltages for each of the digital channels • Bus Configuration VI • The serial bus decoding of the MSO4000 series is a powerful feature. This VI allows the user to completely configure all four serial buses, B1-B4. • The user is able to: • Individually enable/disable the display of each bus • Change the decoding type for any given bus in two mouse clicks • Configure all input sources and decoding parameters for all bus types (listed at far left) • Select the bus display type (Bus and Waveforms, or Bus Only) • Select the bus display format for each bus (Binary, Hexadecimal, ASCII, Signed Decimal, Mixed, and Mixed2) • Adjust the vertical position of each bus and its associated waveforms • Edit the text labels of each bus • Set logic threshold voltages for each channel of a selected bus type • Bus Trigger VI • The MSO4000 features fully configurable triggering on any of the four busses B1 through B4. The Bus Trigger VI is used to select which bus and events to trigger on. • The user is able to: • Select the event type on which to trigger. Each bus type has its own set of potential triggering events, and all of them are represented in the VI. • Configure all of the triggering parameters for the chosen event type. Each type of event has a particular set of parameters associated with it. • Digital Measurement VI • The MSO4000 includes a suite of channel-to-channel measurement and comparison option. This VI allows the user to execute and display the results of measurements between up to four of the digital channels, D0-D15, replicating the scope’s front-panel functionality. • Available measurements include: • Frequency • Period • Phase Difference • Delay • Burst • Positive Duty Cycle • Positive Edge Count • Positive Width • Negative Duty Cycle • Negative Edge Count • Negative Width Sponsored by Tektronix Corporation of America / Faculty Advisor: Dr. Garrison Greenwood Team Members: David Ardito, Jinho Park, David Richoux, Calen Uhlig / Special thanks to Jeff Yost and Ian Dees at Tektronix Department of Electrical and Computer Engineering

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