Design Building Management System with internet technology.

Manh, Thang Pham ; Quang, Vinh Tran

1. INTRODUCTION

All buildings have some form of mechanical and electrical services in order to provide the facilities necessary for maintaining a comfortable working environment. The buildings today not only tend to have modern design, they are also equipped with many high-technology equipments. The designed BMS includes subsystems as follows:

* HVAC subsystem (Heating, Ventilating, Air Conditioning) with sensors of temperature, humidity, air flow and carbon dioxide provides automatic cooling, ventilation and drying control for a specific zone in the house.

* Lighting subsystem controls lamps using local push buttons, moving detection or based on illumination level (darkness). All of the lamps in the specific floor also can be switch on/off by users over embedded web server using TCP/IP technology.

* Appliances control subsystem permits to turn on and off specified devices from inside and outside of the building by SMS messages or via internet. Efficient using of these appliances enables to minimize cost and preserve the environment.

* Energy management subsystem measures the electric consumption like HVAC, lighting, water pumping subsystems. Consumption measurements transfer regularly the power consumption data to a central computer.

* Electronic security subsystem monitors doors, windows and all areas in the house. The system is equipped with magnetic- sensors, glass-breaking sensors, gas detector and all possible intrusions can be detected and signified by SMS messages or via the web server. The browser-based user interface shall utilize latest web technologies, such as AJAX. Security cameras permit the manager to watch what is going on around a building.

* Access control subsystem is implemented with proximity readers, electronic keys and electronic locks. The system can identify and manage the profile of each staff gone into the building by the Radio Frequency Identification (RFID) tags. The system is supplemented with 16 card readers in each floor, where employees are requested to identify themselves.

The main advantages of designed BMS are economy of maintenance and running costs, time saving, increased level of comfort and safety. An efficient BMS brings us greater levels of convenience in our living environments.

2. HARDWARE DESIGN

The CPU of the Ethernet controller board using in BMS is the 100-Pin High-Performance PIC18F97J60 with Ethernet Controller. It's a microcontroller compatible with 10/100/1000 Base-T Networks and integrated on chip MAC and 10Base-T PHY. The features of the chip are: 128k Bytes Flash, 8k Bytes Transmit/Receive Packet Buffer SRAM, 16 channels of 10-Bit ADC (Microchip Technology, 2009). That chip clocks at 25 MHz and obtains two enhanced USART modules supporting RS-485, RS-232 and ICSP interface for In-System Programming. For designed board, we use the 100-pin TQFP packages. Ethernet microcontroller PIC18F97J60 uses 8-Kbytes SRAM buffer between the Ethernet MAC and the internal data bus to efficiently handle high-speed applications.

[FIGURE 1 OMITTED]

The status of the sensors, actuators in the specific floor in the building can be sent via RS485 buses to Ethernet controller board and can be updated or controlled by users from the long range via TCP/IP Networking. The PIC18F97J60 connects to an Ethernet network through 4-pin signal TPIN+, TPIN-, TPOUT+, TPOUT- (Differential plus/minus twisted-pair inputs/outputs) and RJ45 connector. The LEDA, LEDB are multiplexed with PORTA pins RA0, RA1 and can be individually configured to automatically display link status, RX/TX activity (Figure 2).

[FIGURE 2 OMITTED]

For a RS485 communication to the subsystems of BMS, Ethernet controller board uses two pins RC6 and RC7 in the PORT C of microcontroller (Figure 3). For pins RB0 to RB3 in the PORT B are used for 04 interrupts, that can be used for switching ON/OFF the BMS and reserved functions. The Analog-to-Digital (A/D) converter module has 16 inputs, this allow monitor analog input signals such as temperature, humidity or level of human-generated CO2 in the rooms (Ajay, 2005). Other pins of the PIC18F97J60 are used like standard I/O.

[FIGURE 3 OMITTED]

All of the board's schematics and layouts were drawn in the Orcad Capture CIS and Orcad Layout Plus from Cadence Design Systems. The board has designed as double-side PCB. The brief hardware features of Ethernet controller board are as follows:

* CPU: PIC18F97J60, TQFP package, crystal 25 MHz

* Memory: 128k Bytes Flash, 8k Bytes Transmit/Receive Packet Buffer SRAM.

* I/O: 16 analog inputs, 70 standard digital I/O.

* EEPROM: 24LC256, 256KB serial eeprom

* RTC: Real-time clock, DS1307 with 3V Lithium backup battery.

* GSM modem: Siemens Mobile SL 45i [Atmel AVR App. Note No. 323, (2006)].

* LCD: 20x4 alphanumeric LCD type HD44780

* Communication: Support RS485, TCP/IP, GSM.

* Relays board: Opto-isolator, OMRON MY3 Relays

* Operating Voltages: 3.3 and 5 VDC for board's control, 12VDC for Relay's board, 230VAC for appliances.

3. FUNCTIONS OF EMBEDDED SOFTWARE

3.1 Function of application firmware

The physical connection in the TCP/IP network in the BMS is based on Ethernet. The source program of firmware was written in C language bases on Microchip TCP/IP Stack V5.0 and compiled with MPLAB C18 compiler. It is an IDE for the PIC18 PIC microcontrollers (MCU), fully compatible with Microchip's MPLAB IDE, allowing source-level debugging with the MPLAB ICD2. The firmware initializes the board and core stack layers (MAC, ARP, TCP, UDP) and application modules (HTTP, SNMP). The embedded firmware has to ensure the following functions:

* Periodical scanning of the status of BMS subsystems including state of sensors and actuators in every floor in the monitoring building (via RS485 buses). The data of BMS subsystems is updated in the real time to the web server over Ethernet connection (via TCP/IP networking).

* Sending the internet control commands to the BMS subsystems to control of the lamps, switch ON/OFF electrical appliances, HVAC or open electric gates for access in the building. The commands are sent by users from Internet FTP login accounts with passwords.

* Testing, if the some analog values run over the limit or case of security or fire alarm, it will dial, send SMS and email to managers of the building.

The Ethernet controller board is configured for DHCP operation (Olimex Corp., 2009); it should automatically acquire an IP address on DHCP-enabled networks and be available for immediate use in building management systems.

3.2 Function of embedded web server

The strength of Internet technology lies in the fact that information is gathered where it is produced as operation is based on the use of a browser. The web server receives information from the BMS via HTTP. This is particularly useful for multi-operator buildings or by remote control.

The embedded web server using for the designed Ethernet controller board in BMS is written in HTML. The web server utilizes web technologies AJAX and is organized as multiple files within a single directory. The Microchip File System (MPFS) image was been created by command-line utility program, MPFS.exe, that is written for 32-bit versions of Microsoft Windows. Depending on where the MPFS will ultimately be stored, the utility generate either a data file in C, or a binary file. Ethernet controller board using in BMS stored the MPFS image directly in internal program memory of PIC18F97J60 (Microchip Technology, 2008). Dynamic variables allow the web server module to take an each data from BMS subsystems. The browser shall allow at the least the following actions: lighting controls, door controls, IP camera views, modifying the control settings or modifying the mode settings of the controlled device.

4. CONCLUSION

In this report, design and implementation of Ethernet controller board integrated into the building management system are presented. The hardware design and method of firmware and embedded web server development are also explained. The application of Internet technology in BMS has a number of positive effects: Information transfers are TCP/IP standardized; Distances will become irrelevant: once the data enters the network, the distance problems can be solved elsewhere via cable, satellite or wireless. The Ethernet controller board allows improved communication and cooperation between subsystems of BMS. For the real world, the designed BMS will work for building automation and building surveillance in the long range via TCP/IP networking.

5. ACKNOWLEDGMENT

This work is supported by the state research project No. KC03.12/06-10 and Asia Research Center--Vietnam National University, Hanoi.

6. REFERENCES

Ajay,V.D. (2005). Microcontrollers -Theory and Applications, Tata McGraw--Hill Publishing Company Limited, ISBN 0- 07- 058595 - 4, New Delhi

*** Atmel AVR Application Note No. 323, (2006). Interfacing GSM Modem [Online], Available from: http://www.atmel.com/dyn/resources/prod_documents/ doc8016.pdf Accessed: 2007-01-10

*** Microchip Corporation. (2009). PIC18F97J60 Datasheet, [Online], Available from: http://ww1.microchip.com/downloads/en/DeviceDoc/39762d.pdf Accessed: 2009-6-20

*** Microchip Corporation (2008). Microchip AN833 Application Note, [Online], Available from: http://ww1.microchip.com/downloads/en/AppNotes/00833c.pdf, Accessed: 2008-12-12

*** Olimex Corporation (2009). PIC-MAXI-WEB, [Online], Available from: http://www.olimex.com/dev/index.html Accessed: 2009-2-24