【 Weak current College 】 on LonWorks technology in the field of building automation

Building automation system (BAS) is a distributed information and control theory and design of distributed control systems (DCS), which is composed of computer technology, automatic control technology and communication network technologies and human-machine interface technology and mutual development of osmosis [1]. However, the distributed control system is also not fundamentally solve the problem of internal communication system and distributed issue, just as a closed system, to secure the distribution patterns and communication conventions. Therefore, the control system also makes it difficult to adapt to a wide range of intelligent building device detection and control requirements. LonWorks technology is specifically designed for real-time control, can control layer provides interoperable fieldbus technology, as a local area network technology to control the extension and application areas, LonWorks network is to control system according to the local area network (LAN) to construct the network node instead of a LAN of workstations and install it in the monitoring field, directly with the various monitoring sensors and controllers. LonWorks networks each node can be configured as point to point of information transfer, has very good interoperability, so the entire network enables non-Center of real distributed control mode. The network sets data acquisition, analysis, control and network traffic, very suitable for intelligent buildings distributed network management and control. Building automation in recent years are being towards open systems rapidly. In the real-time control, realization of mutual operation of fieldbus LonWorks network communication protocol for building automation LonTalk, sensors, actuators and networked operations between controllers.

2.LonWorks technology overview and applications of building automation system

2.1LonWorks technical brief

Echelon LonWorks technology is a United States company 90 years December of a fieldbus technology, Lon (LocalOperatingNetwork) mean for local action network, have all fieldbus technology. Field bus is a bus, it's automated communication system in the computer field at the lowest level of low-cost network. International Electrotechnical Commission (IEC) and the Foundation fieldbus (FF) for field bus made the following definition: Fieldbus is connected smart scene equipment and automation systems of digital, bi-directional transmission of more branch structure of communications networks [2]. At present, many of the world famous automation manufacturers and Honeywell, JohnsenControls, ABB, Philips, Hp, etc. are LonWorks technology. To date, using LonWorks technology manufacturer already has more than 3000, and install 500 000 nodes. In China, Echelon Beijing Representative at its establishment in 1995, and currently has 60 Chinese manufacturers joined the LonWorks control networks OEM, LonWorks control networks technology has been widely used in all major industrial areas, such as industrial plants, building and home automation, agriculture, health and transport sectors, etc. LonWorks distributed measurement and control network technology, it truly and completely to implement the "decentralized control, centralized management control thought, in international and domestic are becoming more widely used. More accurately, LonWorks technology effectively addresses distributed control

2.2LonWorks technology main features

LonWorks network system by intelligent nodes, each node can have multiple functions of the I/O functions. Users can further programming a node, implementation of user-defined algorithms and features. All the nodes that are available through different transmission media for data transmission, and follow the ISO/OSI 7 layer model of LonWorks technology including monitoring network design, installation, development and debugging of a set of methods that you want to use a variety of specialized hardware devices and software programs, including the following:

2.2.1LonWorks technical core is Neuron Chip Neuron

This use of Neuron Chip CMOSCLSI technology to achieve low-cost network control possible. In Neuron chip has three 8-bit CPU, the first CPU processor for media access control, handle the LonTalk Protocol is the first and second floors, which includes driver communication subsystem hardware and implementing conflict avoidance algorithm; the second CPU for network processor, processing, LonTalk protocol layer 3 to layer, it network variables handling, addressing, transaction processing, confirmed, background diagnosis, software timer, network management and function path selection and so on, it also controls the network traffic, and physically send and receive packets; a third CPU for application processor that performs user-written code and user code called by the operating system services. Neuron Chip programming language as it is from NeuronC ANSIC derived from, and to reduce the book ANSIC and additions. A running NeuronC Applications node, you can note 62 network variables. A network variables can be NeuronC variables or structures, its maximum length can reach 31 bytes. Up to 31 bytes of an array can be embedded in a structure and as a network variables to spread. Neuron Chip has a very versatile communication port, it has five pin, use the five pin can be configured to a variety of communications media interface (network transceivers). Neuron Chip from a 5-pin communications port or with 11-pin i/o port to send and receive information. These pins can be used in different configurations, to external hardware offers a flexible interface and access time clock chip. I/O port there are four categories of 34 preprogrammed I/O object that is used to achieve effective measurement, timing and control applications.

The core technology of 2.2.2LonWorks as LonTaLk communication protocol

Protocol followed by the International Organization for Standardization (ISO) defines the open System Interconnection (OSI) model, providing 7 layer protocol for all content of the service. In the communication on the use of an improved CSMA (carrier monitoring multiple access), known as the zone forecast P-PersistentCSMA algorithm.

2.2.3LonTalk protocol supports a variety of transmission media

Such as twisted pair and power line, ultrasonic, infrared, and optical fiber, etc. Each of these media is called a channel, each channel has a dedicated transceiver as intelligent node and communication media interface devices. Different transmission channels available through the router for Internet. In the different media with different transfer rate, up to 1.25Mbps, transmission distance up to 2.7Km, each channel maximum 3.2 000 nodes.

2.2.4 in network architecture, LonTalk protocol support decentralized correspondence PeertoPeer

Nodes can be composed of bus, ring, tree, and so on many kinds of network topology and composition free topology. Network communication uses object-oriented design methods that you can use a technique called NeuronC programming language.

2.3LonWorks and building automation

Building automation is all power in the intelligent construction, the building equipment for automatic monitoring and control system, it usually consists of a central management station, communication controllers, DDC, sensors and actuators, such as the composition of distributed control systems (DCS) is an open network communication system. General building automation can be divided into two parts for open systems: part is considered low-speed part, mainly related to sensors, actuators and controller of the immediate environment; another part is the high speed section, mainly involving large amounts of data transfer and advanced network environments, such as alarm handling, order priorities as well as dynamic data exchange, open database connections, etc. Building automation system in its place communication between a workstation is typically based on Ethernet network or the TCP/IP Protocol, and the lower traffic controller and the communication is based on the DDC RS-232, RS-442 protocol that employs a peer or token control of information transmission.

PROFIBUS is a communications technology, which uses digital instrument replaces the analog instruments for serial communication mode to replace the traditional 4 ~ 20mA analog signal, a fieldbus can for a large number of addressable field equipment for multipoint connections, support for the underlying field intelligent equipment and high-level system over a public transmission medium for the exchange of information. More critical is a new generation of FCs FCS instead of a traditional distributed control systems (DCS), the implementation of the communication network and control system integration. Traditional DCS adopts "action stations-control station-field instrument" three layers and a slave, the fieldbus input/output modules, control station features decentralized to field intelligent instrument. Each instrument has its own CPU modules for measurement, control, diagnosis, output, and other functions. Each instrument has become one of the nodes in the bus, between the nodes through the fieldbus connection, any failure of a node do not affect the other node. Therefore, it has better than DCS FCS superior relationship structure and DCS system key difference abolished the huge centralized control branch, and the measurement, control, and sensor divided into smaller units, and integrate into the accused objects to the computing capacity to diversify and to use the object focused superior computer complete the system of coordination. LonWorks network intelligent node contains temperature detection, relative humidity measurement, carbon dioxide detection, damper actuator, VAV, fan-coil control and constant temperature controller, chiller, unit ventilators, wall hanging detector, valves, actuators, alarm and alarm management, data and trend analysis, etc. Based on the LonWorks network technology for building automation system, as shown in Figure 2, the comprehensive and integrated computers, control and communication technology, uses the distribution, fieldbus, such as the structure of a distributed control system and the advanced management technology. It is mainly composed of a large number of dispersed in intelligent buildings inside the device subsystem, as well as core they are measuring, monitoring, control, management and coordination of LonWorks intelligent nodes, including:

2.3.1 changes the electrical power distribution system

LonWorks point intelligent node (SinglePointSmartNode "SPN) have a Neuron microprocessor and the network interface that allows to nodes exist in the LonWorks network, it can be used as a temperature and humidity sensor, single output relay nodes. Can smart building supply situation for real-time monitoring and control, including all levels of power switching equipment, high-voltage power distribution Cabinet and the low pressure side of the main circuit, current, voltage and power factor, the temperature of the transformer and cable, the generator running, monitoring and control, and on failure alarm etc; in addition, through the power of measurement and statistics, scientific management, reasonable balanced load to ensure safe, reliable power supply.

2.3.2 air-conditioning system

Programmable intelligent node in LonWorks (ProgrammableSmartNode hereinafter referred to as PSN). PSN is a customized based on device monitoring program of small controllers for system installation provides the ability to generate custom control program. PSN for small air conveying, cooling towers, heat exchangers, etc, its applications and internal operating system stored on PSN in non-volatile memory. For different regions of the air conditioning system prepared in advance by timing or under environment temperature automatic control for building air conditioning refrigeration units, cooling water pumps, cooling fan, electromagnetic valves, fans, and monitors and records the status of the device, the measured points between indoor and outdoor temperature and humidity, air pressure, flow, valve opening and running timeAnd other parameters, automatic fault alarm or downtime, animate the water valve, fans of location, status, etc.

2.3.3 elevator system

LonWorks based on host intelligent node (Host-basedSmartNode "HSN) provides two types of application: its a LonWorks network can be connected with other networks (such as Ethernet) communications gateway; disulfide may apply to some large non-packaging equipment systems of control applications. Elevator is building an important hub for traffic. On the elevator with a complete installation, use this node to control devices and building automation systems for data communication between the Central Administration to be able to grasp the working conditions of the various lifts, and fire, security, and other special occasions on the elevator runs direct control.

2.3.4 lighting, water supply and drainage system

LonWorks of ASN is a chip containing Neuron, network interfaces, the necessary input/output and storage resources small controller, it can be achieved by designing and programming such as VAX tank, heat pumps, fan coils, package of HVAC equipment control provides a way for packaging equipment systems for low-cost solution. Application specific intelligent node (ApplicationSpecificSmartNode hereinafter referred to as ASN): according to the establishment of time series, on the floor of the power strip, Office lighting, corridor lighting, garden or Park, Office lighting, advertising, neon lights, decorative lights, Aviation Festival obstacle lights and other equipment automatic start-stop control and automate the lighting circuit for grouping controls, on electricity too large of an automatic shut-off, as well as the halls and offices, "no one lights" control. On the pump, pump, sewage water pump running, water tanks and sewage pool water level monitoring in real time, and through the monitoring of the water supply system pressure and water level, under the pressure of the State, start and stop the pump to ensure the normal operation of the drainage system.

2.3.5 fire fighting and security system

LonWorks, enter output module (IOM) is the main task of the IOM and the temperature and humidity sensors, control relays, sensors and control device interface. Based on the LonWorks of IOM unit's input is on those traditional sensing and monitoring information, such as temperature, humidity, flow rate, air quality, alarm status and so on; the output is used to control the fans, pumps, lighting circuits, relay, fire protection system is an intelligent building automation, it is an important component of the building fire safety systems fire hydrant, spray water, fire pumps, regulators pumps, fire, smoke, temperature sensor detection alarm, fire smoke exhaust valve, fire elevator, fire radio, fire telephone fire device networking monitoring and automatic control, in the event of a fire the immediate adoption of building automation systems, electrical, plumbing, air conditioning, elevators, and other related system gives access to the fire mode command from the device's own control system to coordinate and implement fire action. And through CCTV monitoring and access control, intrusion alarm security patrol, and other basic means to identify a run object, flame, smoke and other abnormal status and alarm and automatic video recording, on the channel to access object to control the maximum guarantee of security.

Intelligent building building automation subsystems are coordinated with interoperability characteristics, therefore also need to have a centralized management and coordination of the system, so that each subsystem can organically integrate together constitute the building automation network. Taken together, support various of LonWorks network field intelligent nodes, can make the sensors, transmitters and actuator itself with data processing and data communication functions, they are very effective in supporting the building equipment system consisting of the application, can be easily formed a truly distributed monitoring network.

3 closing


At present, intelligent building development platform usually consists of three-tier network constitutes, at the top are the communication automation of communication network, in the middle is a local area network for Office Automation, the lower is used for building automation and control networks. For a network-based distributed processing system, the hierarchical structure on the construction of an effective, robust, low-cost design is required. Using LonWorks network building automation system, using LonWorks network as distributed console, device communication connections to form the complete functions, composition and flexible and intelligent building control system, remote communication monitoring system, etc, and may be based on the need for flexible configuration and extension. Clearly, the building automation system uses this kind of hierarchy, and the world's most popular network protocols TCP/IP, ensuring complete compatibility with the rapidly evolving world of computer and network compatible, good open, avoiding the control-level network of unnecessary changes to meet different application requirements.