Client-Server Measurement System using LabVIEW for Educational Use Adela Vintea, Paul Schiopu Faculty of Electronics, Telecommunications and Information Technology University Politehnica of Bucharest Bucharest, Romania adela.vintea@ieee.org , schiopu.paul@yahoo.com Octavian Ghita, Sorin Grigorescu Faculty of Electrical Engineering University Politehnica of Bucharest Bucharest, Romania octavian.ghita@upb.ro , sorin.grigorescu@upb.ro Abstract—The today concern in educational software is to allow students maximum flexibility and autonomy in their laboratory work, combined with higher accuracy of measurements. This paper present a client-server system used as a virtual instrument for laboratory, built with LabVIEW stand-alone subVI’s, designed for several different laboratories in the Electrical Measurements Department. Such systems are intended to work both in local or remote network configurations, being a vital component in Distance Learning. Keywords - Client-server model, LabVIEW, Virtual Instrumentation I. INTRODUCTION One of the advantages of virtual instrumentation is to allow a certain degree of autonomy for students during laboratory activities and to provide fewer resources, such as equipment or space, in order to achieve the same teaching goal. Establishing “virtual” working measurement places not only help students doing their own measurement readings but allow teacher to note better their efforts. Also, instead of connecting the client to a local server, the connection can be done via Internet, thus allowing e-learning and e-laboratory facilities to the concept of Distance Education. II. CLIENT SERVER MODEL LabVIEW was long time used in the laboratory activities of Electrical Measurements Department within the Electrical Engineering Faculty. To optimize the teaching methods, at first for the Virtual Instrumentation courses, but then also for Numerical Measurements and Signal Processing courses, a stand alone application in LabVIEW was implemented [1]. The application was designed first to allow the implementation of time behavior for a dynamic analysis for first degree and second degree converter. The real setup includes a Metrix Oscilloscope and a signal generator in a RLC montage that are connected to a computer where the server is installed [2]. Of course, from this example, other laboratory exercises can be implemented, including power measurements or indirect methods (A-V) for determination of impedance in A.C. Figure 1. Schematic of dynamic regime analisys for a 1-st degree converter For the time analysis of a first degree converter, the computer based server application is able to acquire the signal as viewed by the oscilloscope, the communication driver allowing the setting of baud rate and the protocol used to transfer data. Also, the communication port can be changed, depending of the real port of PC used to connect with Metrix scope. Students or users can see in the window, both signals: the theoretical one, drawn under the schematic, figured with gray and the real acquired one, exactly in the scope window, figured with red, as presented in figure 1. In this example, the oscilloscope Metrix work with 4 channels, 2 physical and 2 mathematical channels. The physical channels are no.1 and no.4 so the student can understand which signal is coming directly from the signal generator and which is passed through the RC circuit ( in our example, channel 4). After establishing the values for R and C, the students can observe the direct connection between these values of parameters and the behavior of time constant and rise time: at each increasing of R or C values, the rise time and time constant increase proportionally, which is an important