requirements document forPLCCS: A Power Line Carrier Communications Systemsubmitted to:Professor Joseph PiconeECE 4512: Senior Design IDepartment of Electrical and Computer EngineeringMississippi State UniversityMississippi State, Mississippi 39762January 24, 2000submitted by:W. Kwan, W. Parker, B. Roberts, J. TatumFaculty Advisor: Dr. Nicholas YounanDepartment of Electrical and Computer EngineeringMississippi State UniversityBox 9571Mississippi State, Mississippi 39762Tel: 662-338-5361email: [email protected], [email protected],[email protected], [email protected]: Communications System 1ECE 4512 03/17/00EXECUTIVE SUMMARYTechnology in today’s world is advancing at a very rapid rate. Once a rare commodity,computers can now be found in hundreds of millions of homes and businesses [1]. A growingtrend involving computers is industrial control and home automation, a practice in whichelectrical devices are controlled with little or no human interaction [2]. Although this may soundlike a noble concept, many of these control systems suffer from poor performance in terms ofdata communications capability [3]. They also require the user to configure them locally, whichmakes it difficult to check the status of the systems from afar. Also, many systems carry a steepprice tag that many potential buyers find unappealing [4].To remedy the first of these issues, a new data communications system will be developed. Thesystem will consist of one or more host units and multiple target units. The host units willinitiate all data communications processes to the target units, and a target unit may reply only tothe host that hails it. Only one communications process may exist at any given time per host,preventing data communication collisions. Existing electrical wiring will serve as thecommunications medium, preventing the expense of installing additional wiring in the building.The access issue will be remedied by designing a software package for a personal computer. Thesoftware will allow the host device to connect to a PC, as well as the Internet using TCP/IP. Theuser will therefore be able to access the host device through a standard Internet connection.A third issue is the cost of comparable control systems. Presently-available systems that are usedin industry cost thousands of dollars [4]. By programming a microcontroller to emulatetraditional hardware, less electronic components will be required to build a working system. Asa result, overall production costs will be substantially lower than comparable systems. Theproduction cost of each host and target unit will not exceed $35 and $30, respectively. Theexpected market price of a host unit will be $149.95, and the expected market price for eachtarget unit will be $39.95.We will approach this project by dividing it into several key components. A modem will bedesigned that will allow the host and target units to communicate over the power line.Microcontroller firmware will be created to control the functionality of both host and target units.Circuitry and firmware will be implemented to interface the host unit to a PC. Software will bewritten to allow user-control over host and target units.Our design will be superior to presently-available device control systems in that ours will reducethe number of control errors due to corrupted data transmissions, thereby enhancing thereliability of the system. It will also provide an easy-to-use interface that will allow users torender remote control over all host and target units and all of their associated peripherals.Considering the ongoing growth in popularity of home and industrial control systems, this projecthas an abundant future [5]. Potential design enhancements include improving the data transferrate of the modems and enhancing the remote web interface.PLCCS: Communications System 2ECE 4512 03/17/001. PROBLEMIndustrial control and home automation has rapidly been gaining popularity for the past decade.Although many automation and control products are available on the market, many of thememploy a modulation technique that was developed twenty years ago. This technique utilizessimplex communications, which simply means that the modules that control electrical equipmentare capable only of receiving data and not transmitting. As a result, the modules have no way ofinforming the host controller if they properly received a data transmission. Because of this, datafrom the host is often received as corrupted, and erratic equipment behavior may result.A second issue encountered with these systems is that many of them utilize a host unit that isunable to interface with a computer network. In this technological era, it is almost a necessity toprovide an interface between sophisticated electronic products and a PC. This certainly appliesto controls - why even buy a control system unless you can access it while you are away?To remedy the communications issue, our team will develop a more reliable method of datatransmission. This will ensure that more data will successfully reach the target device whilebeing transferred over a building’s noisy wiring, which will in turn lessen the number ofinappropriate switchings by the secondary units. In effect, the system owner will no longer haveto spend time attempting to fix an uncorrectable problem.The accessibility issue will be resolved by designing a user-friendly computer interface for thesystem. With this interface, users will be able to remotely check the status of their systems,therefore eliminating the worry of discovering that their “controlled” devices are on the blink.Users will also be able to remotely make changes to the operation of their devices to comply withtheir schedules.PLCCS: Communications System 3ECE 4512 03/17/002. OBJECTIVES1. Data Transfer Rate: The data transmission speed of the power line carrier will be a minimum of 300bits-per-second and a desired 600 bits-per-second. 2. Error Rate: An average of 1.5 data packets or less will be required for a message to successfully beexchanged. 3. System Structure: The system will be able to support up to a total of 4.29 billion host and targetunits. 4. Browser Compatibility: The web interface will be compatible with Netscape 3.0 and MicrosoftInternet Explorer 3.0. 5. Power Usage: The host
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