Group SD0611
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SD0611 Power Line Instant Messaging
Group Members
Oluwasijibomi Saula
Tyler Schumacher
Andrew Teevens
Advisor
Dr. Chao You
Introduction
The SVEE Home in West Fargo, North Dakota, provides assisted living for individuals with developmental disabilities. Given the limited staff of the home, automation is desired to improve services. A major concern of the SVEE Home is the proper use of appliances such as refrigerators and climate controls. The power line instant messenger (PLIM) is a system that facilitates communication necessary to control and monitor appliances.
The basic idea of PLIM is to utilize the existing power lines of the SVEE Home as communication channels. These communication channels serve as paths of automation. Messages and commands are sent over power lines to control and monitor devices and appliances. The PL 3150 smart transceiver from Echelon Corporation is integrated into the PLIM network to execute power line communication.
PLIM is a three unit prototype network built to demonstrate the functionality of power line communication and appliance automation to the SVEE Home. Two units demonstrate point-to-point communication over the power line network. The third unit functions as a PC interface and data logger. These PLIM units are the backbone of the network and execute the power line communication. The completed prototype units are shown in Figure 1.
Summary Of Impact
There have been several attempts to improve services at the SVEE Home. These attempts have included the use of radio frequency (RF) devices that control access to pantries, an automated medication dispenser that distributes medication at specific times, and a mechanism that controls access to the refrigerator at the SVEE Home. All three devices are individually designed, operate independently, and require separate training and maintenance. Such characteristics are not convenient for the SVEE Home staff.
The PLIM system forms an integrated and unified network for SVEE Home automation tasks. Although the prototype PLIM network currently does not control any appliances, existing ones such as the refrigerator door control as well as future applications can be integrated into the system with some effort. Instead of a bunch of appliances and devices acting on their own, these appliances will be a part of a centralized and shared communication network. Time on training and maintenance is less since appliances are integrated in the network and the way to operate them is more uniform. Appliances can be controlled and monitored from various PLIM units around the house. PLIM network is limited to using the wall outlet for power and may be susceptible to power line noise.
Technical Description
The three prototype units and their interconnections are illustrated in Figure 2.
The two point-to-point communication PLIM units, or instant messengers, are made up of three hardware parts: 1) a PL 3150, 2) an LCD, 3) and a keypad. The PC interface and data logging unit simply consists of a PL 3150 and serial cable to connect to the PL 3150.
The PL 3150 smart transceiver is the core of the PLIM unit. The PL 3150 uses an Echelon protocol, LonTalk, to transmit data over the power line. Custom code programmed in the Neuron C language sets up the communication network and implements point-to-point communication. Special functions in the code also drive the LCD and keypad. Future applications only require minor code adjustments to add new appliances and new PLIM units to the network. The PL 3150 is plugged directly into the wall outlet to ensure that the impact of noise or interference on the message is as small as possible. The PL 3150 requires 12V to operate and then distributes 5V to power the LCD and keypad.
The LCD uses the serial cable to transmit and receive data from the PL 3150. The LCD is programmed with a character map. This character map enables the PL 3150 to identify which character to print on the LCD according to which button is pressed on the keypad. The keypad uses a parallel connector to send the ID of the button pressed to the LCD. In turn, the LCD sends the ID to the PL 3150 which prints the character on the LCD. The built-in LCD and keypad are beneficial in that they give the user the ability to view alert messages without being at a computer screen and to type and send messages/commands to control appliances from various locations without being right at an actual appliance.
The third PLIM unit is the PC interface and data logger. This PLIM uses the serial cable to send messages to the computer. With software that reads data in from serial ports, the PC can display the message and can also log or store the message for future reference. This logging ability allows SVEE Home supervisors to keep track of network activities such as who accesses a refrigerator or pantry.
The PLIM devices offer secure, sound, and efficient communication and control. PLIM uses the common outlet for power so no expensive batteries are needed. PLIM is a user friendly network since it is easy to operate the devices and add in appliances. However, some appliances may require more effort to add to the network. The cost for one PL 3150 is $99.95. The three PL 3150s needed to create this communication system will total to $299.85. The cost may increase to accommodate unique needs of specific appliances. Price for wiring and three enclosures came to $160.00. With two LCDs ($69.95 each) and two keypads ($13.13 each), this system cost $626.01. This PLIM system totaled $466.01 since Echelon Corporation graciously donated three PL 3150s.
Software Langauge Information
Application programs for the PL 3150 to run the communication system, LCD, and the keypad are built in Neuron C. Each PL 3150 is a node in a communication network or domain. SCI UART is the type of computer hardware that is in use to receive and transmit data packets. Variables called network variables in Neuron C are used to store messages and are then updated and transmitted across the network. Network variables come as input or output network variables. Output transmits while input receives and stores data. For our network variables to send/receive messages an address table has to be constructed. This address table would tell the program where data for the input network variable comes from and where the data is transmitted to for the output network variable. In our program we use group address tables to transmit messages to multiple devices. The difference between group address table and a normal address table is group tables are able to transmit to multiple devices as long as those devices have the same group address table declared. Normal address tables can only communicate with one device. Finally a network variable table needs to be set up where a list of all network variables is contained. Here the network variables are assigned to the address table they belong to and the network variables they can communicate with on other devices, keeping in mind that output can only work with input and input can only work with output. In our program we have ASCII string-type network variables transmitting and receiving messages from multiple devices using group address tables.
Group table Picture:
Project Documents
Click on the name of the document you wish to view and then a new page should appear. Here click on the name of the document again and it should download.
Requirements Capture:File:RequirementscaptureFinal2.doc
Options Considered: File:OptionsConsidered.doc
Progress Report: File:ProgressReport.doc
Final Paper: File:FinalPaper.doc
User's Manual: File:UserManual.doc
