Remote Monitoring of Multi Parameters Using an Embedded Digital ...

Remote Monitoring of Multi Parameters Using an Embedded Digital Controller

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Remote Monitoring of Multi Parameters Using an Embedded Digital Controller A. Balaji Ganesh1 and A. Lakshmi Sangeetha 2 1

Embedded and Applied Computing Laboratory, TIFAC- CORE, 2 Department of Electronics and Instrumentation, Velammal Engineering College, Chennai-66

ABSTRACT: This paper focuses on the remote monitoring of multiple process variables interfaced through an embedded digital controller. The system allows the remote user to accomplish the network mediated remote operations with a dedicated local computer. The study includes the design and development of both the hardware and the software. The hardware part includes the design and development of an embedded based data acquisition system (DAQ) that has been used to interface four number of process variables and consequently monitor it from the local computer. The software part focuses on the development of the internet remote front panel for the remote operation. Beside that, the software includes development of virtual instrumentation (VI) system that has successfully replaced the physical measurement system. The developed model of this study has been used for data acquisition, network communications, instruments monitoring and controlling applications.

Keywords —DAQ, Multivariable, Embedded System.

INTRODUCTION

SYSTEM DEVELOPMENT

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The controller is built around the PIC16F877 on microcontroller board. The digital controller provides three primary functions: controlling locally the process functioning as thermostat, reading as well as displaying the digital temperature from the PT100 sensor and maintaining parallel communication with a computer. This system includes a cost effective design solution with minimum hardware and maximum support of software to achieve a user-friendly virtual instrumentation based programmable temperature controller, to control temperature range from— 200oC to 850oC, with menu driven support for selection of the control functions. The paper develops four channel data acquisition system to incorporate four different processes such as temperature, pressure, flow and level. In order to maintain the desired state of slow and optimal processes we need to keep constant, at prescribed values, such variables as flows, pressures, levels, temperatures, concentrations etc., which demands the design of automatic control systems for them. On the one hand the control systems for these variables differ from one another through their structure and behavior in dynamical state. On the other hand, the automatic control of one of these variables presents, in principle, the same problems, no matter what the process associated with it is, therefore the control systems are treated as subclasses associated with these physical measures: flow, pressure, level, and temperature. The advent of embedded based digital controller combined with user friendly software program assures desired performance, simplicity, flexibility and reliability for temperature monitor and control. The digital controller is connected using parallel port to a

he continuous development and progress in the computer field and networking technology has enhanced the use of the existing computer features in the field of the measurement and test instruments, which in turn has enhanced the collaboration between geographical distributed research and development centers. The classical circumstance for the distributed instrumentation system is the distributed system in space, where different instruments are located at one place; the main control rooms are located at some distance, and the measurement data processing, analyzing and storage at remote location. Another circumstance of the distributed instrumentation system is when the direct control or monitoring of the instruments as in hazardous areas. Networking has been introduced successfully in the instrumentation field to interconnect different instruments and data processing sites into a distributed measurement system in literature [1]. Recently, Lakshmi and Ganesh (2008) have presented an embedded based digital controller for thermal process [2]. A web mediated digital embedded controller for thermal process has been discussed and presented [3]. The main goal of this study is to design and develop a network-based control system and investigate the performance of the system on the network. The network can be created on a small scale as the intranet or over a large scale as the internet. The study in this report mainly focuses on the process control system over the Wide Area Network (WAN) which is the internet. Through the network link the communication between the two sides; the system and the remote operator, takes place as they are physically in the same location.

Remote Monitoring of Multi Parameters Using an Embedded Digital Controller personal computer on which the instrument application runs. Desired temperature (reference) is introduced using a computer keyboard locally. This value is transmitted using the parallel port from the computer to the digital controller. In the four channel system it is possible to interconnect sensor system which offers voltage and current as their output component including temperature, pressure, flow and level. The source code for the microcontroller is written in assembly language and front panel is designed using Microsoft Visual basic. The photocopy of four channel embedded digital controller system is shown in Figure 1.

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data acquisition is still occurring on the host computer (instrument server), but the remote user (client) has total control and identical application functionality. However, to prevent the confliction between different remote users in performing remote control actions, only one client can control the front panel at a time.

DATA VISUALIZATION AND ANALYSIS The study performs to monitoring four different processes through a unique data acquisition board and results of this finding are shown in Figure 2. Basically, there is no difference between executing the remote operation through the single channel data acquisition system of the four channel data acquisition system as the executed steps are exactly the same. To ensure the program works over the internet as it has been planned, it was tested several times from outside the college campus over the internet server. The internet service is provided via the broadband connection.

Fig. 1: Digital Embedded Controller

INTERNET BASED REMOTE OPERATION The test that has been conducted on the instrumentation system is the remote monitoring and control operation. The first step in this study is to enable the PHP based visual basic executable remote front panel since the PHP along with visual basic program supports the remote operation through a remote executable file. For security purposes, and to protect the system from unauthorized person access, the virtual instrumentation program of this study has been kept with the authorized person. Once the user get the executable remote operation program from the operator, the user will be given with a username and password. Once the username and the password are provided, this program will automatically direct the remote user and the user can start the remote operations. The remote front panel allows users to monitor and control any virtual instrumentation remotely from the visual basic front panel without any programming. This feature greatly expands the applications of the remote operations as an operator can run a system from anywhere and at anytime as long as an access to the communication network is provided. Besides that, several users geographically distributed can access the same virtual instrument ation simultaneously. Through the remote front panel, remote clients can monitor as well as control the real-time system parameters on the local computer front panel as opposed to static images. The

Fig. 2: Web Based Remote Operation

One important notice worthy to be mentioned for the remote operation and it has been noticed from the program execution of this study, as the remote user is away from the server (local computer), the program is very sensitive to the commands sent from the client side. Due to that, the clients have to follow and carefully execute the operation steps as they are ordered in their numbering sequence. It is recommended that a local operator attends the server, if possible, to fix any problems could be initiated accidentally by the remote clients. Beside that, at this stage of this program development, a remote user can not save the measurement data on the client computer if the client is not sharing the same network with the server.

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CONCLUSIONS In this paper, the feasibility of the remote operation over the intranet or the internet have been experimentally investigated and proven. This study focused on the design issues, investigation and implementation of the internetbased monitoring of a dynamic system. The study covered the two sides of this issue, the software and the hardware. The electrically heated water bath temperature system is considered as case study and local digital controller is effectively interfaced with a transmission rate of 10 µs. Web architecture based low cost virtual instrumentation (VI) system to monitor the parameters such as temperature, pres sure, voltage and level has been developed with a better throughput that merely depends upon internet bandwidth.

Mobile and Pervasive Computing (CoMPC–2008)

REFERENCES [1] Smiesko, V. and Kovac, K., 2004, Virtual Instrumentation and Distributed Measurement Systems, Electrical Engineering Vol. 55, 50–56. [2] Lakshmi Sangeetha, A. and Balaji Ganesh, A., 2008, An embedded based digital controller for thermal process, Sensors & Transducers Journal, Vol. 87, Issue 1, January 2008, 46–51. [3] Lakshmi Sangeetha, A. and Balaji Ganesh , A., 2008, Web mediated digital embedded controller for thermal process, Proceedings of ICVLSI’ 08, 213–215.