Customer Solutions

Electronic Instrumentation Laboratories on the Internet

Author(s):

Andrea Bagnasco, University of Genova; Marco Chirico, University of Genova; Walter De Michelis, University of Genova; Alan Rossi, University of Genova; Anna Marina Scapolla, University of Genova

Industry:

University/Education

Product:

LabVIEW

The Challenge:

Handling the increasing demand of distance and continuous education on electronics through the remote access to an electronic instrumentation laboratory on the Internet.

The Solution:

Designing and implementing an interactive Web-based environment, the Electronic Test Bench (ETB), consisting of programs (VIs) and guided experiments on basic circuits. The environment takes advantage of the new features of LabVIEW and the Internet Developers Toolkit, optimizes the distribution on the network of the instrument interfaces, and allows access to a virtual laboratory.

Introduction
The term "virtual laboratory" refers to a representation of the laboratory which is distributed on the network and permits access and control of laboratory on instrumentation and software simulation.
Using virtual instrumentation we were able to meet our challenge in a timely and cost-effective manner. Moreover, virtual instrumentation systems dramatically reduce the time required to develop complex test programs, potentially unifying the separate worlds of test and measurement, and industrial automation. The proposed approach provides the following advantages:

• Students can remotely operate laboratories
• Laboratory instruments can have multiple student users
• Students can "design" their own experiments
• High-cost instruments can have many student users
• Students can use resources efficiently
• Virtual laboratories can become part of distance-learning curricula
• Standardization of course/laboratory format can ease authoring and enlarge the availability of teaching/ training material

Electronic Test Bench Provides Laboratory Online
With ETB, students can practice with instruments and execute measurement experiments on electronic circuits across the Web. On the student side, it consists of an introduction to the virtual laboratory, a set of online instrument manuals and a set of experiments/lessons for gaining knowledge of instruments and measurement procedures.

Each lesson has a didactical target and offers a collection of exercises to conduct using the virtual instruments. Hypertext guides students to connect test circuits to the instruments and stimulate them with known signals to analyze the answers.

A waveform generator and an oscilloscope already exist in the ETB. A student starts the instrument panels, presses buttons, rotates knobs, and views the results of these actions on the screen as if acting on real instruments. With the control panel of the waveform generator, students can choose different kinds of waveforms and the variation of waveform parameters, such as amplitude, frequency, offset, duty-cycle. Similarly, with the oscilloscope interface, students can visualize one or both channel(s) and set various parameters, such as time scale, amplitude, vertical and horizontal shift, trigger setting, and screen brightness.

A Look Inside the ETB
The ETB consists of three macro-blocks:

• Web site
• ETB server
• ETB clients
  

The Web site provides the delivery of hypertext and virtual instrument panels. We installed a G Web server, which is a HTTP server supplied with the Internet Developers Toolkit. The Web also provides the helpers for the clients configuration.

The ETB server consists of the instrument drivers and simulators of the circuits under test (unit under test - UUT). The instrument drivers and simulators are independent software modules and communicate by means of global variables. Each instrument driver receives input commands from the clients and simulates the real instrument behavior. These commands are formulated according to the IEEE 488 Standard. In this way, we can reuse the same software modules both for real instrument control and for simulation.

The ETB clients are distributed on the Internet. They run the instruments and UUT interfaces. The instrument front panels are very realistic because of heavy customization of basic LabVIEW elements. The communication between the clients and server has been realized using the VI Server features and, in particular, using the Call-by-Reference Node function, which lets us set the communication through TCP/IP in an easy and functional way.

For more information, contact:

 Andrea Bagnasco, Marco Chirico, Walter De Michelis, Alan Rossi, and Anna Marina Scapolla

Department of Biophysical and Electronic Engineering

University of Genoa, Via All’Opera Pia 11/A - 16145

Genoa, Italy

Tel: +39-10-3532267

Fax: +39-10-3532175

 E-mail: chirico@dibe.unige.it

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