Author: Mrs into
One. introduction
The objects that need to be monitored in the intelligent building are: HVAC system, water supply and drainage system, distribution and lighting system, transportation management system elevator system and parking system, fire automatic alarm and fire linkage system, public safety system. In the 1980s, computer centralized control and monitoring were used, and the reliability was poor. Computer Distribution Control (DCS) mode has taken more than 90% since the 1990s. Currently, distributed control is a development trend.
The discussion of this article is how to build a remote control platform for intelligent buildings based on the BACNET protocol and the Java language, expand the resource resource-limited device such as mobile phone into the end of this network, which is more convenient to implement all-round control.
two. Feasibility Analysis
1 BACNET
The BACNET Network Communication Agreement is an open standard for the US State Standards Bureau (ANSI) by the US HVAE (ASI), which is approved by the US State Standards Bureau (ANSI). An open standard for the manufacturer of the building automation system, and the ASHRAE learns Comprehensive several local area network LANs (notice that the industrial control network) is developed, which is developed as much as possible of the LAN network.
June 1995 BACNET became the ASHRAE B5-90 standard, and the owner has put forward higher requirements for integrated technology due to the development of network and communication technology, requiring building automation systems to strengthen contacts with high-level enterprise management systems. Improve management efficiency. That is to say to interconnect the information management network, solve the effective way for different manufacturers' automation system integration. Therefore, manufacturers can develop with BACNET compatible controllers or interfaces in this standard protocol to achieve mutual exchange data. BACNET has a more large data communication than Lonmark, operating advanced complex information. It is a communication technology that can achieve the interconnection between the building automation system of different manufacturers. For example, a set of BA systems such as Honeywell or Johnson communicate with other public security and fire protection systems to communicate them into a whole through the BACNET and all monitoring of these systems can be implemented on a workstation.
2 Connect to the Internet through BACNET
The BACNET extension protocol is specified in Appendix J in the BACNET protocol: BACNET / IP, which makes BACNET be more open, we can access BACnet in any place in the Internet to provide the foundation for our remote control scheme. And combine the security strategy of the Internet's own security strategy to the security policy of the BACnet itself, it can ensure the security of the data transmitted on the network.
3 Java Technical Introduction
The Java language is originally an object-oriented language born to develop electronic consumer products. Because the Internet has just been born, the performance of the cross-platform execution of the Java language has caused broad interest in the network programmers and is booming.
There are multiple versions of the Java language, where we have to use Java 2 Micro Edition (J2ME, also known as kjava). This version is designed specifically for resource-limited devices such as mobile phones. He is a simplification of the Java Standard Edition.
After the manufacturing of MOTO, SIEMENS and other equipment, the two standardization results of Kjava were released in 1999.
The first, interconnected, Limited Device Configuration, CLDC, is posted on October 1, 1999. The purpose of this outcome is to define components and libraries for a large number of different small, interconnected, resource-limited equipment. Java programming language and virtual machine features, core libraries, input and output, network security is the primary topic processed by the CLDC specification. The CLDC does not position any particular device category, more appropriate, he defines the general purpose build block, which defines the description specific to a variety of devices. 18 companies have participated in CLDC standardization. The second standardization result, the Mobile Information Device Profile, MIDP starts at the end of September 1999. Based on CLDC based on CLDC, the increased features and API functions are set in two-way wireless communication devices. Application model, user interface, network, and storage API are the main concentration fields of MIDP specifications. 22 companies participated in the MIDP expert group work.
4 Use J2ME to connect to internet
A scalable universal network connection framework is provided in the CLDC specification, which includes six basic interfaces.
A basic serial input device
A basic serial output device
A communication device for datagram
Communication equipment exchanged in a surface circuit
A Notification Mechanism informing Server - Server Connection
A basic web server connection
In MIDP, these interfaces are implemented, so that MIDP can request the Internet to serve the Internet through the HTTP protocol, but based on flexibility and the particularity of the content discussed herein, we will give up the convenient HTTP protocol and use the underlying Socket connection. There are two advantages to this.
1. Easy to customize the data structure with the BACnet device;
2. You can encrypt the transmitted device to the client (ie, the mobile) to enhance security.
5 Communication for remote mobile devices and BACnet devices
Here we use the indirect connection method, that is, the mobile device and the BACnet device are connected to a server on the Internet in the internet.
The server listened to the remote device to make a province verification and related analysis, and then perform the corresponding instructions to get the execution result, then return to the remote device.
three. Prospect application
After the BACNET protocol is connected to the remote device, we can view the temperature, settles, alarms, or any other permissions anytime, anywhere. In addition, due to the Internet, we can apply computer powerful data processing capabilities, and data sampling will be more accurate in real time. In addition to the user, it can easily control the indoor electrical appliances in an off-site, which makes the building more humane, and bringing a busy modern person.
We believe that the use and development of new technologies will have a new look to the world.
references
1 Mainstream technology of intelligent construction and its application Lu Wei Liang
2 About some major technical and development trends in intelligent buildings, please
3 BACNET and Internet interconnect Xu Zhengyuan Zhang Yi Fumeheng Xinwang Automation Engineering Co., Ltd.
4 Remote control model based on GPRS
