Research On Web-based Remoteplatform For Electrical Measurement And Control

Experiments are an indispensable link in college teaching.With the development of modern network technology,the introduction of network remote control technology into university laboratory equipment and projects is becoming more and more common,which combines curriculum experiments and engineering projects,virtual simulation and field experiments.Compared with traditional field experiments,all resources are open to students at school and to the public,which makes learners the subject of experimentation,at the same time,it's extremely open,interactive,efficient,universal,and lifelong.This article combines the network remote control with the universal electrical measurement and control experiment platform to provide an independent online experiment platform implementation program.The electrical measurement and control experiment platform based on ARM Cortex M4 and FPGA is universal.We can expand the design to construct a wide range of input and output channels.Input and output analog channels with a wide frequency range and high-precision can be configured with real-time signal hardware acquisition,storage,analysis and processing functions.Also,PC software can also be used for later analysis and processing,which offers the channels a wider range of applications.This platform can achieve signal detection,acquisition,storage,processing,analysis,signal generation,control,drive,and a mixture of both applications.This article takes the design of the frequency characteristic test instrument as an application example to verify the performance of the electrical measurement and control experiment platform.The frequency characteristic test instrument uses DDS(Direct Digital Frequency Synthesis)technology to generate sine wave swept frequency signal data with the frequency range of 100 HZ to 10 MHz.The digital sine wave data are generated by the DDS built in the FPGA and converted to an analog sine signal through a high-speed D/A converter.The signal then drives the network under test after passing through the signal conditioning circuits.The response signal of the measured network passes through the signal driver circuits,collected by the A/D converter and then input to the FPGA to obtain the amplitude data and the phase data of the excitation signal which has passed through the measured network.Excitation signal generation and input signal amplitude detection and phase detection are further processed and controlled by an ARM system based on the Cortex M4 core and the TM4C1294 controller to obtain the amplitude and frequency characteristics of the network under test.This article introduces the network remote control into the universal electrical measurement and control experiment platform mentioned above,which can realize remote development,design,debugging and testing.For the convenience of future upgrades and maintenance,as well as the extension and flexibility of the experimental content of the system,the network remote control system adopts the B/S(Browser/Server)mode and logs in to the client browser to access the server.Utilizing LabVIEW execution system commands(System Exec.vi function)and LabVIEW webservice technology to remotely call the CCS command line tool to remotely create,import,compile,and download CCS programs with no need of opening the CCS software development environment.In addition,we use FileZilla software to set up an FTP server to implement FTP file transfer,including file uploading and downloading.