Open system in automation of the hottest intellige

2022-09-19
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Open system in intelligent building automation

at present, the building equipment automation system (BAS) in intelligent buildings contains more and more equipment and subsystems, which are more and more complex. Because different products and systems provided by different manufacturers have greatly improved the stability and reliability of the system, their different communication protocols will result in different communication rates, coding formats, synchronization methods, and communication procedures, which makes it difficult for these products to achieve interoperability and system interconnection. If various equipment and subsystems in the system operate independently without interconnection, the integrated and coordinated operation cannot be carried out, which will affect safety management, energy conservation management, low management efficiency, difficult maintenance, and high expansion and maintenance costs

1. Why adopt open standards

at present, the owners and managers of intelligent buildings urgently need to reduce costs and improve efficiency. They require that the system of the building be integrated together, and there must be an effective way to realize the integration and interoperability of the system and equipment. Therefore, the system needs to be truly open. Bas suppliers, building equipment manufacturers and owners hope to realize product interoperability and convenient connection of subsystems, which leads to the concept of open system

the so-called open system means that all components of the building equipment automation system are manufactured with recognized industrial standard technology. The system conforms to the recognized industrial structure, so the products of different manufacturers can be combined to realize interoperability. It has two characteristics:

1) the technical specifications of the system are followed by all manufacturers

2) although components with the same function are produced by different manufacturers, they can be replaced and operated mutually

at present, there are two open standards in the world: one is lonmark standard, and the other is BACnet standard. These two standards have also been recommended by relevant standards in China, such as 3.1.10 in the general provisions of 3.1 in building equipment automation system (BAS) in the local standard "engineering design standard for intelligent building systems" db32/db32 of Jiangsu Province, which clearly points out that for the integration between different systems of multiple suppliers, the ANSI/ashare SPC 135p standard of BACnet formulated by ASHRAE society of the United States should be adopted. Lonmark standard should be adopted for distributed control system. These two standards are introduced below

2. Lonmark standard

lonmark standard is a set of standards based on LonWorks technology. LonWorks technology was developed and launched by echelon company in the United States in the 1990s. LonWork technology is actually a measurement and control technology, or more precisely, an industrial control technology, also known as fieldbus technology. It is convenient to realize the connection of sensors, actuators and instruments on site

this network is different from local LAN, but an industrial control. Because it transmits detection information, status information and control information with a small amount of data. Echelon is called local operating network (lon). Lon adopting lontalk protocol is called LonWorks

lonworks technology has the following characteristics:

● LonWorks technology is a set of open technology, and its communication protocol lontalk protocol is also open, making it possible to realize the interconnection of products that comply with the agreement

● the key chip of LonWorks technology, neuron chip, has a high degree of integration, with three 8-bit CPUs (CPU1, CPU2, cpu3) inside. CPU1 is responsible for media access control, and CPU2 and cpu3 are responsible for network communication. In addition, there are ram, E2PROM, ROM, and i/o interfaces inside

● LonWorks technology supports a variety of communication media. Including twisted pair, power line, coaxial cable, optical fiber, radio frequency, infrared, etc., and even a variety of media can be mixed in the same network

● LonWorks has a complete range of technical products. There are more than 50 hardware and software modules in four categories, and advanced development equipment and means bring convenience to user development

it was popularized worldwide in 1993, and its development speed is extremely fast. By 1995, 2500 manufacturers have used and installed more than 2 million nodes (each node includes a neuron chip, which can have an average of 5 measurement and control points). Its development speed is far faster than any other fieldbus (such as CANbus, PROFIBUS, etc. if the dynamometer is not installed horizontally before and after). It is used in building equipment automation system (BAS), industrial automation, aerospace technology and other fields in intelligent buildings (large hotels, restaurants, office buildings, modern high-end residential buildings). However, more than 50% of the nodes are used in the field of building automation. All major building automation companies and industrial control companies in the world agree that LonWorks technology is currently "the most advanced" and "has great potential", "this technology will cause directional changes in the control market", and said that they would use this new technology to transform their products. Therefore, a large number of OEM manufacturers (more than 1000 important OEMs) have been formed all over the world, producing a large number of LonWorks technology products. Most of them are products supporting building automation systems. Although different OEMs manufacture products according to LonWorks technology, they cannot interoperate because they are not unified in some technical details. In order to solve this problem, 180 important OEMs formed the lonmark interoperability Association and compiled a series of lonmark standards, so that each technical detail has strict provisions of standard documents. Where products are produced according to this regulation, they can be combined to communicate and work with each other. Similar products produced by different manufacturers can be replaced with each other. In short, interoperability is achieved. Such products are decorated with lonmark marks

lonmark protocol is divided into HVAC group, household equipment group, lighting group, industrial group, intrinsic safety group, network management group, oil group, refrigeration technology group and access control group. Each group is developing a series of lo to enhance the nmark standard, called functional profile, which describes the application layer interface in detail. Including network variables, configuration features, default values, network nodes, power on status, etc., to standardize product functions

the compilation standard of HVAC first published in March 1996, including temperature detection, carbon dioxide detection, damper actuator, roof unit control, variable air volume control. Subsequently, temperature controllers, refrigerators, unit ventilators, wall mounted detectors, valve actuators ", alarms and alarm management, data recording and trend analysis, etc. were successively compiled

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