【 Weak current College 】 uses LonWorks (r) technical design of the building control system

（BuildingAutomationSystem）

China Construction Group · Beijing North yellow automation equipment installation co., Ltd., Liu Yan Feng Guo-ping Jin ju chill

I. preface

The early 1990s, born LonWorks (r) open distributed control networks, which allows manufacturing light small, low-cost, intelligent control equipment (SmartIntelligentControlDevices), these devices built with standards of LonWorks (r) network communication protocols and control functions of the intelligent microprocessor CPU, these agreements with Ethernet network (Ehernet), fully compliant with ISO standardization Committee to develop the seven layers of the network protocol, these protocols by the United States Echelon LonWorks based company provided to independent developers (LonWorksIndependentDevelopers, LID), and intelligent microprocessor CPU from Motorola, and United States Japan Toshiba manufacture. This new technology allows different product independent developers to design and manufacture of the product directly together, without intermediate conversion devices (such as Gateway, Router, etc.); these are based on the LonWorks (r) Protocol products include:

HVAC building air-conditioning system

FlowControllers flow controller

FireDetection & Prevention fire detection and prevention

PowerDistribution power monitoring

AccessControl credit cards, access control, intrusion control system

Transceivers & Modules network communication transmission receive adapter

CCTV closed circuit monitoring system

Detectors & Sensors sensors, detectors and implementing agencies

ParkingEquipment garage management equipment

ControlNetwork: DevelopmentTools Web development tools

Lighting lighting system

ControlNetwork: Management network management system

Elevators lift system

ControlNetwork: the basic structure of the Infrastructure network

I/O input/output devices

Miscellaneous other kinds of equipment

EnergyManagement energy management system

Audio & Video and sound equipment

Communications network communication

GeneratorSets generator equipment

MMI (ManMachineInterface) man-machine interactive interface

　

For any network-based distributed control system, to practical engineering to design an efficient, powerful, and good cost performance of the system, the network architecture is and its importance. In a different control level, require different system characteristics, different communication media and different communication speed. A system must be in each level, meet the applicable technical requirements.

This article describes the control system network architecture used the LonWorks control networks (r) as a decentralized control device (ControlHorizontalLevelDevice) communication connection, while in the communications backbone (RiserbackboneLevel) with Ethernet and TCP/IP Protocol, through Ethernet-LonWorks (r) Routers router connected to your corporate LAN and wide area networks including: Intranets and the Internet. This and structured cabling (PDS) to complete and implement all subsystems truly integrated.

Second, the LonWorks (r) control network technology compatibility (different manufacturers of products between connectivity, interoperability)

Development and design of LonWorks (r), control purpose of network technology is to make all the different products from different manufacturers are compatible between each other, just like the computer industry. Owners and engineers want compatibility and open system benefits, therefore, this system should meet the following requirements:

2.1 in order to ensure system interoperability and connectivity, all products should have the LonMark certified (products on LonMark (r) tags), from node i/o traffic data should be a standard network variable types (StandardNetworkVariableTypesSNVT ' s); further said that it was essential for all based on the LonWorks (r) of the node to provide external interface file (XIF) to ensure that the user will be able to maintain the system, adjust the system's operation and expansion of the system.

2.2 designed system Lontalk Protocol must be used to install the system, you can use standard, other manufacturers develop HMI software MMI as user interface. MMI system adopts SNVTs as communication data. If the FIX, INTOUCH, CITECT, etc.

2.3 can adopt standard, otherManufacturers developed software kit, network management, maintenance and configuration, such as the LonPoint, VisualControl, MetraVision and PathBuilder VisualIntegrator, and so on.

2.4 in order to reduce the system cost, improve system performance price ratio, in the design of the system, you can open market purchase from many manufacturers of generic LonWorks (r) equipment, these devices include: SmartControllers (intelligent controller), Rouers (routers), CommunicationInterfacesNetworkCard (NIC), the Sensors (sensors), Actuators (actuator).

Third, building control control system network architecture

Control system design is the first step is to select a different type of control equipment to meet the needs of a variety of control system, for example: for PackagedHVAC air-conditioning system, VAV VAV system and HeatPumps dedicated controller for larger control systems such as air handling units, chillers for programmable intelligent universal controller for sensors and actuators of a single point of intelligent controllers, specifically as follows:

3.1 single point smart controller (SinglePoint "SmartNodes", SPN)

Single point of intelligent controller SPN is some equipment, such as temperature and humidity sensor, a single relay output devices, power and power of sensors, etc., which are built-in neurons microprocessor (NeuronChip) and network interface card (NetworkCard), LonWorks (r) network as a single node exists, allowing a more decentralized control system.

3.2 dedicated controller (ApplicationSpecific "SmartNodes", ASN)

Dedicated controller ASN is very small, they are designed for specific devices, built-in factory pre-programmed in expert mode and algorithms, such as air conditioning system, VAV PackagedHVAC VAV system, HeatPumps and fan coil unit FanCoilUnits etc. These intelligent controller built-in neurons microprocessor (NeuronChip) and network interface card (NetworkCard), has the necessary input and output terminals (I/O) and memory resources to execute specific control tasks. ASN is not a freely programmable, built-in in the expert mode on ASN and the algorithm is saved in the nonvolatile memory (such as FLASHEPROM).

3.3 programmable intelligent universal controller (Programmable "SmartNodes", PSN)

Programmable intelligent universal controller PSN is a very small controller, users can free programming to meet the corresponding device control needs, they are widely used, such as: air handling units (AHU), chillers, cooling tower, heat exchanger, etc., the user application and control of the monitoring program is stored in the PSN on non-volatile memory (such as FLASHEPROM).

Application of PSN ' s, ASN ' s, SPN ' s controller of LonWorks (r) of the chart control network system as follows:

3.4 network intermediate nodes ("Meta-Nodes", MN)

Network intermediate nodes MN performs two functions: a function is the LonWorks control networks (r), can be used as connection to Ethernet (or other network) communication gateway (CommunicationGateway) or server (Server); another feature is that they can in the LonWorks control networks (r), perform advanced control tasks, these control task is very large, ASN and the PSN is unable to complete the control task requires large amounts of data and complex analysis, computing; MN typical control applications include: central control unit, a very large system of control and so on.

MN ' s is also called "HostedNodes", the controller board of neurons microprocessor is used with LonWorks NeuronChip (r) communications, control tasks from the controller on a different microprocessor implementation, such as: Intel80486 and Pentium; as "HostedNodes", MN can handle 4096 SNVT ' s, and the PSN ' s, ASN ' s, SPN ' s controller can only handle 62 SNVT ' s.

In a typical control application, MN controller read i/o module and PSN ' s, ASN ' s, SPN ' s acquisition of the data controller, there will be a large amount of data analysis and complex calculations, such as optimal restart/stop control, etc.

In a typical communication gateway applications, MN controller as LonWorks (r) control network node, at the same time it connects to Ethernet (or other network) backbone; they also serve as the communication gateway to provide other non-LonWorks (r) network interface interface, MN controller in LonWorks (r) network and other systems to carry out the necessary protocol conversion. The user application and control of the monitoring program is stored in MN on non-volatile memory (such as FLASHEPROM, EEPROM and battery-backed RAM).

3.5I/O modules

I/O module is the most important role is to provide regular, non-based on the LonWorks (r) of sensor and controller interface interface, such as: temperature sensors, relays, do water valves and air valve and so on, based on LoNWorks (r) i/o module input connection these conventional device monitoring information, such as temperature, humidity, flow, switching value, and so on, output connection control equipment such as: fans, pumps, lighting circuits, relay, etc.

These I/O module built-in neurons microprocessor (NeuronChip), they do not execute control tasks, their system is the collection of regional data information, provide them over the network to the system of the other intelligent nodes, these intelligent node information based on these data control decisions.

The above on MN ' s, SPN ' s, ASN ' s and PSN ' s discussion, we conclude the following control system chart:

3.6MN controllers at the system level level of networking

In a large, control system, you may need multiple MN controller, so we must be established between these network nodes; communication network depends on system size and performance requirements, the regional networks can be control-level network (LonWorks (r) network) to connect various controller node or a standard enterprise wide area network such as Ethernet backbone.

LonWorks (r) network and LonTalk (r) Protocol has proven to be control node information exchange between the fastest and most reliable tools; in addition the network offer a lower price than the node access and high flexibility of the network topology, simplifies the installation process, allowing no relay of long-range transport, offers a wide variety of transmission media, including: twisted pair, fiber optic, power cord, RF, these features make the LonWorks (r) network is the ideal application-level network of control.

However, if the requirements for high-volume data communication with Ethernet Ethernet backbone as system may better; Ethernet in Office Automation to transfer large amounts of data and information; the use of Ethernet Control backbone of another advantage is that it uses the TCP/IP Protocol (so far, the world's most popular network protocol), so the control networks with enterprise-level network such as Intranet and Internet easy integration. This ensures that the rapidly changing computer and network technology compatible, protection and control network does not make unnecessary changes. For these reasons, it is recommended to use the system's backbone, and Ethernet control level using LonWorks (r) network.

Based on these requirements, MN controller should be built-in Ethernet communication capabilities (via a simple docking module), so that the design of BAS system provides powerful scalability to meet different application requirements.

Using multiple networked MN controller and Ethernet as the backbone of the system, its structure is as follows:

3.7 control level of networking/system node capacity

Control-level network should be the LonWorks (r) network and using Lontalk (r) Protocol, LonWorks (r) network, with free topology can be connected into a star, bus and ring, LonWorks (r) technology also allows different media types, such as: mixed twisted pair, radio frequency power cable, and fiber.

LonWorks (r) network system structure support Lontalk (r) protocol specification limit, that is, 255/domain node/subnet 127, so each domain system capacity is 32,385 node.

3.8 system redundancy design

LonWorks (r) network architecture allows for fully distributed control possible.

IV. action man-machine interface (MMI)

Control system should allow the operator through computer graphics display interface of dynamic real-time observation of field equipment of health, in order to meet this requirement, the system should allow the user to use the standard, other manufacturers are development, based on WINDOWS95/NT HMI software toolkit, such as: Intellution fix and Wonderware Intouch of, these products must be able, through its built-in communication driver software and DDE or OPCServers exchange information with the control system.

4.1 multiuser/remote access features

Control system should support multiple user access, allows multiple users simultaneously online operations, will be in a position to support Internet by Modem and remote access.

4.2 programming/systems installation

Control system should allow users to compile their own control program in order to meet unique application and system needs.

Control system of programming should have produced complex logical language features (such as IF/THEN ... ELSE, GOTO, and so on) in order to optimize HVAC system; should support: PID adjustment, optimal restart/stop control (OptimumStart/Stop), set point reduction (SetpointReset) and so on.

Standard kit with 4.3 compatibility requirements

Control system should be allowed to use the standard Echelon Toolkit to initialize node installation, in addition, the control system should also be allowed based on the LonWorks (r) Protocol Toolkit for system installations, such as: VisualControl, PathBuilde MetraVision and VisualIntegrator, etc.

4.4 physical connection with workstation

System management workstations (PC) should be able to use all standard LonWorks (r) protocol supported network interface card (such as: SLTA, PCNSS, PCC-10, PCMCIA, etc.) connected to a LonWorks network (r)Complex.

4.5 support portable communication tools

Control system should be able to support the same portable communication tool of information exchange such as the Pager (machine), etc.

5. alarm information, real-time communication, display, print

Control system of alarm information should be able to pass the following communication tools in real time display, print and sound like the police, as a system of minimum configuration requirements, such as a modem to dial out (Modemdial-out), personal pager (PaqgerorBeeper), phone (MobilePhone), etc.

6. control system integrated with other systems

Control system should be able to pass MN node built-in LonWorks (r) communications protocol with other system completely integrated, MN nodes should also be able to through RS232, RS485, Ethernet to communicate with other systems.

7. vendor technology certification

System integrators should be familiar with LonWorks (r) technology and the ability to skillfully use based on the LonWorks (r) products, control systems for programming and debugging.

System integrators should independently or together with the manufacturer, as pre bid technical demonstration of the system, your system will show all critical equipment operation, including smart programmable controller DDC, user/machine interface (MMI) software, installation and programming of the controller, the alarm message is displayed and printed.