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In accordance with the definition of the International Electrotechnical Commission IEC/SC65C, installed in the manufacturing or process areas and the control room to field devices between the digital control devices, serial and multi-point communications data bus known as the field bus. According to applications and uses of different field bus is divided into low-speed Fieldbus H1 and H2 high-speed fieldbus. IEC/SC65C H1 bus is used for the initial definition of manufacturing or process areas, through two power transmission lines to the field of low-speed serial bus devices, H2 bus is no need to solve the two-wire power supply for high-speed transfer information between devices serial bus. H1 and H2 bus complementary and form a complete industrial automation system information communication network.

After 15 years of debate, IEC61158 for industrial fieldbus control system to international standards has finally passed in early 2000, followed a struggle for fieldbus low tide, IEC/SC65C/WG6 Fieldbus Standards Committee also completed a history of this mission. In order to further improve the IEC61158 standard, IEC/SC65C established MT9 fieldbus Amendment groups to continue work in this area. MT9 Working Group 8 in the original type of field bus based on the expansion of continuous improvement, in August 2001 to develop 10 types of the composition of the third edition of the fieldbus fieldbus standards, they are: Type1 TS61158 field bus, Type2 ControlNet and Ethernet / IP fieldbus, Type3 Profibus fieldbus, Type4 P-NET Fieldbus, Type5 FF HSE Fieldbus, Type6 Swift-Net field bus, Type7 WorldFIP Fieldbus, Type8 INTERBUS fieldbus, Type9 FF H1 Fieldbus and Type10 PROFInet site bus, the standard in April 2003 as the official international standard. Due to space limitations, this type of bus do 10 kinds of outlines and briefly reviewed the bus the latest progress of the last three years.

1 Type1 TS61158 Fieldbus

Type1 fieldbus standard by the following components:

PhL: IEC61158-2: 1993 standard superset (Superset);

Superset of Foundation Fieldbus;

WorldFIP functional superset;

DLL: IEC TS61158-3, TS61158-4;

Superset of Foundation Fieldbus;

WorldFIP functional superset;

AL: IEC TS61158-5, TS61158-6.

Before 1998, IEC/SC65C only recommend one type of field bus, the bus main bus and the adoption of Foundation Fieldbus bus WorldFIP basic technology and developed in strict accordance with IEC fieldbus standard defined for various reasons, after many rounds of voting has not been by only a technical report in accordance with the provisions of TS61158, as a basis for the formation of the present Type1 fieldbus. International Electrotechnical Commission recommended a common field bus network shown in Figure 1, can be seen from the figure field bus system can support a variety of industrial fields of information processing, monitoring and control system for process control sensors, actuators and local low-level communication between the controller, the PLC can be achieved with the interconnection of factory automation. Here, H1 Fieldbus is mainly used for the field level, the rate of 31.25Kbps, responsible for two-wire power supply to field instruments, and can support bus-powered devices with intrinsic safety; H2 Fieldbus primarily for process control level, monitoring and management-level and high-speed factory automation applications, the rate of 1Mbps, 2.5Mbps and 100Mbps.

2 Type2 ControlNet and Ethernet / IP fieldbus

By the ControlNet International (CI) organization is responsible for the Type2 fieldbus standard consists of the following components:

PhL and DLL: ControlNet;

AL: Control Net, and Ethernet / IP.

Type2 fieldbus system architecture shown in Figure 2. ControlNet uses a new mode of communication, that the producer / client (Producer / Consumer) model that allows all nodes on the network, while data from a single source of access to the same data, the main feature is to enhance the system functions, improve efficiency and achieve precise synchronization. Media delivery network access, by restricting access algorithm to control the time that the parallel time domain multiple access (CTDMA) method, each network update interval (NUI) adjust node transmit information within the opportunity.

Ethernet / IP Ethernet industrial protocol is an open industrial network that uses active-star topology can be 10Mbps and 100Mbps product mix. The protocol TCP / UDP / IP on top of additional control and information protocol (CIP), to provide a common application layer. Control of part of the CIP for real-time I / O packets, some of their information for the message exchange. ControlNet and Ethernet / IP is the protocol communication, sharing the same object library, object and equipment line rules, making multiple suppliers of equipment can be achieved in the whole network plug and play. Object is defined strictly in the same network to support real-time messages, configuration and diagnostics. In order to improve the real-time industrial Ethernet performance, ODVA (DeviceNet open Suppliers Association) in August 2003 announced a IEEE1588 “for Ethernet / IP real-time control applications, clock synchronization” standard.

3 Type3 Profibus Fieldbus

Type3 are Fieldbus Profibus user organization PNO support, Germany's Siemens is a leading supplier of Profibus products. Profibus-compatible family of three components, namely Profibus-DP, Profibus-FMS and Profibus-PA 3 BUS. Profibus bus to improve performance, in recent years PNO launched a new version of the Profibus-DP-V1 and Profibus-DP-V2, while phasing out of Profibus-FMS bus. Extended Profibus-DP field bus architecture shown in Figure 3, Profibus-DP device level suitable for automatic control systems and distributed I / O high-speed communication between. Profibus-PA for process automation design, it can be connected to the transmitter and the implementation of a public bus line can be completed using the two power supply and data communications, and to realize essential safety performance. On this basis, the extended DP functions DPV1 to further improve the Profibus-PA function; DPV2 solve the communication from the station and time synchronization between the major problem.

Profibus-DPV1 key is to increase the non-cycle services, and expanded the main station with two classes of communication. As we all know, Profibus-DP performance is characterized by a cycle of connection (Mscy-C1) on the basis of application data exchange services, the realization of a master and a series of focus from the exchange of data between stations. Master Class 1 refers to PLC, PC or controller. Category 2 refers to the main station operator stations and other programmers. DPV1 extends these capabilities, the existing Mscy-C1 connection basis, an increase of non-cycle services, the use of new services can be any data from the station group read and write. In the past, Class 2 DP master can only use the free connection service from the station, and now may be connection-oriented communication through an array of non-cycle read and write, at the same time expanding the access to Internet communications capabilities.

Profibus-DPV2 cycle of communication can be achieved, non-cyclic communication and communication between slaves. Because direct communication between slaves, communication time a DP bus cycle and the master cycle, so that the reaction time shortened from 60 to 90 percent, while establishing a time interval such as a bus cycle, the time deviation of less than 1?s , that is suitable for high-precision positioning control, but also to achieve closed-loop control. DPV2 may need to be developed according to different application-specific norm (profile), such as for motion control ProfiDrive and interlock protection for ProfiSafe so.

4 Type4 P-NET Fieldbus

P-NET Fieldbus from Denmark Process-Data Sikebory Aps company began developing in 1983, mainly used in beer, food, agriculture and husbandry, which are P-NET User Organization's support, at the scene about more than 5,000 applications .

P-NET Fieldbus is a multi-master, multi-network system, Figure 4 gives the P-NET system architecture. Bus with sub-structure, each bus can connect multiple sub-master station, master station can be achieved through the interface between the interconnection line, which allows direct addressing in several bus zone without hierarchical network structure. The bus communication protocols, including 1,2,3,4 and 7 layers, and using the channel body defining user layer. Communication with the virtual token (virtual token) transfer mode, the master sends a request to be addressed within the immediate return from a standing 390?s response, only stored in memory from the station can be accessed in the data. Each station node contains a common single-chip microprocessor, supporting 2KB EPROM can be used not only communication, but also can be used for measurement, calibration, conversion and applications. P-NET interface chip implementation of all the features of the data link layer, Layer 3 and Layer 4 functionality from the host processor in software solutions. The bus, RS-485 physical layer standard based on the use of shielded twisted-pair cable, transmission distance 1.2km, asynchronous transfer application NRZ coding.

5 Tpye5 FF HSE Fieldbus

In 1998, the United States Fieldbus Foundation (FF) Foundation decided to use high-speed Ethernet (High Speed Ethernet, HSE) technology development H2 field bus, field bus control system as the above control level backbone communication network, which integrates with the H1 Fieldbus constitute an integrated and open information architecture, Figure 5 shows the system structure. HSE Ethernet network follows the standard norms, and according to the need for proper process control to increase the number of features, but these additional functions can be structure in the framework of the standard Ethernet to operate seamlessly, so the bus can use the FF HSE currently popular commercial (COTS) Ethernet equipment. 100Mbps Ethernet switch using a star topology is connected, this switch has a firewall to block specific types of information access network. HSE uses standard IEEE802.3 signal transmission, a standard Ethernet connection and communication media. The distance between devices and switches, using twisted pair for the 100 meters, fiber optic cable up to 2 km. HSE used to connect devices (LD) to connect H1 subsystems, LD Executive bridge function, which allows in-place even in the H1 field devices on the network to complete the peer peer communication. HSE supports redundant communications, any device on the network can be configured for redundancy.

FF HSE 1 to 4 layers from the existing Ethernet, TCP / IP and the IEEE standard definitions, HSE and H1 uses the same user layer, fieldbus message specification (FMS) in H1 defined service interfaces, on-site equipment Access Agent (FDA) for the HSE to provide interfaces. Function module provides user level, device description (DD), function file (CF), and system management (SM). FF standard function modules for 21 basic and advanced process control use. FF also provides a new flexible function blocks (FFB), to complex batch and hybrid control applications, FFB support data collection monitoring, subsystem interfaces, sequence of events, multi-channel data acquisition, PLC, and other protocol communications gateway.

6 Type6 SwiftNet Fieldbus

Type6 SwiftNet Fieldbus hosted by the American Association of SHIP STAR enacted by U.S. support for Boeing, mainly used in aviation and aerospace industries. The bus is a simple, real-time high in the bus, the agreement includes only the physical layer and data link layer. SwiftNet stratified Bus fieldbus topologies, the communications architecture in Figure 6.

Physical layer transmission rate of 5Mbps, then 105 different per second transmission packet. Bus using the TDMA (Slotted time division multiple access) time slots Road access way to send multi-chip, providing dedicated high-speed, low-jitter synchronization channel and the specified channel as required. Dedicated channel for automatic allocation or exchange of state data; requested channel is designated for non-scheduling message. TDMA mode is the time the bus is divided into equal length intervals, called slots Road, only when the bus stop assigned to the Tank, it can monitor and send. Each station is also available under the share, coordinate bus access, data transmission and reception of data.

SwiftNet bus node (slave) via I / O channel connecting smart sensors, as in aerospace sensors and actuators with high requirements to start using the bus line IEEE1451.1 and IEEE1451.2 standard network sensors. IEEE1451.2 “for sensors and actuators Intelligent Interface Devices” standard is an open standard, it is in the control network and define a standard interface between the sensor so that a field bus system network sensor field-level digital sensor, enable users to choose according to their needs smart sensors from different manufacturers to achieve true plug and play.

7 Type7 WorldFIP Fieldbus

WorldFIP association established in 1987 to develop and vigorously promote Type7 WorldFIP Fieldbus. WorldFIP agreement is the third part of the European standard EN50170, the physical layer IEC61158.2 standards, its products occupy 60% of the market in France, in Europe, about 25% share of possession, it is widely used in power generation and transmission and distribution, process automation, railway transport, metro and process automation.

WorldFIP Fieldbus architecture shown in Figure 7, the system is divided into three levels, namely, the process level, control level and control level. It can meet user needs, suitable for all types of application structure, centralized, decentralized, and master / slave type. WorldFIP bus to meet with a single process control, factory processing and manufacturing needs of a variety of drive systems. To meet the requirements of low-cost, developed a low-cost Device WorldFIP (DWF) bus, which is a network device, can well adapt to the harsh environment of industrial site and has intrinsic safety explosion-proof performance, can achieve more than primary station and the communication from the main station.

WorldFIP agreement by the physical layer, data link layer and application layer. Data link layer bus adjudication, in any given moment, only one station can perform the bus arbitration functions, it uses a ID-DAT frame broadcast a logo on the bus, all stations connected to the bus link layer ID-DAT were also recorded frame, only one station was identified as identity producers, just as users of other stations. MPS and SubMMS application layer provides services, MPS is a factory cycle / non-cycle services, SubMMS is a subset of industrial message.

8 Type8 INTERBUS fieldbus

Type8 INTERBUS field bus developed by the German Phoenix Contact, INTERBUS Club Club support. INTERBUS more than 1,000 buses in the global equipment manufacturers and provide more than 2500 kinds of products, so far, INTERBUS field of automation in the world has more than 50 million sets of widely used applications.

INTERBUS Fieldbus is an open serial bus, you can create various topological forms, and allow for a 16 nested connection. The bus up to 512 field devices can be linked to, the maximum distance between devices 400 meters, no repeater network maximum distance 12.8 km. INTERBUS remote bus and local bus, including bus, remote bus for the remote transmission of data using RS-485 transmission, the network itself is not power supply, communication rate of 500Kbps and 2Mbps. INTERBUS loop has its own unique structure, the loop using a standard cable to transmit data and power simultaneously. Loop can be connected to analog, digital equipment and even sophisticated sensor / actuator, but also allow direct access to intelligent terminal devices.

The agreement includes the physical layer, data link layer and application layer. Data link layer process-oriented data transmission method and lumped frame agreement, can transmit data and the cycle of non-cyclic data, the frame information includes a start signal, send back information, data security / end information. Lumped frame with very high transmission efficiency, the efficiency of up to 52%, although rates of 500Kbps and INTERBUS communication 2Mbps, communication speed and high efficiency. Application layer services for real-time data exchange, VFD support, variable access, the program calls and 12 related services.

INTERBUS bus has a strong monitoring diagnostic function, the bus monitor function monitors the entire network operation of the system state, while Ye bus network to provide the variable structure function, in time according to design requirements, and Lian Jie bus off the Mouge sub-bus segment. Monitoring is on-site installation, commissioning, diagnostics and maintenance of a powerful tool. Specific function is to identify and determine the installation errors and components, error, field bus module with input / output status display, set the output when the debug state, and you can save some of the smart device parameters.

In order to improve industrial network security, to meet the manufacturing and process automation fail-safe communication requirements, especially in the automotive industry has a safety function of the bus was the first place. INTERBUS Club started in 1999 INTERBUS bus safety study, in 2001, organized by the German BIA standards EN954-1 KAT.4 permit and comply with IEC61508 safety communications standards. INTERBUS safety bus control module by a Safe Control and on-site distributed intelligent modules, control modules, whose sole function is to control the security of data. This solution scheme is superior to other programs, it will control the system and security of Gongneng bus distinct from, clear and simple control system agencies, without prejudice to future of Kuozhan and Xiu Gai, Cheng Ben obviously Jiangdi. This is a Fieldbus direction.

9 Type9 FF H1 Fieldbus

FF Fieldbus H1 is responsible for the formulation of the Fieldbus Foundation. FF Foundation members from the world's leading instrument manufacturers and users, the members of the production of transmitters, DCS, actuators, flow meters accounted for 90% of the world market, their field of industrial process control network, a thorough understanding of functional requirements, In the process control has accumulated rich experience, propose a more comprehensive field bus network architecture, the communications architecture shown in Figure 9. Type9 Type1 Fieldbus Fieldbus is a subset.

FF H1 fieldbus protocol from the physical layer, data link layer, application layer and taking into account the control field devices and specific applications to increase the user layer. H1 bus supports a variety of transmission media: twisted pair, cable, fiber and wireless media. Transfer rate 31.25Kbps, maximum communication distance of 1 900 meters. The bus supports bus-powered and intrinsically safe.

Data link layer is responsible for scheduling activities to achieve the link, the receiver sends the data, active response, the bus link between the device time synchronization. Here, the bus access control activities using the link scheduler (LAS) method, LAS has a list of all devices on the bus, the bus segment which is responsible for all equipment on the bus operation.

Fieldbus application layer by the field bus access (FAS) sublayer and Fieldbus Message Specification (FMS) sub-layer. FAS sub-layer provides publisher / subscriber, client / server and report on three models of message distribution service. FMS sub-layer provides object dictionary (OD) service, variable access services and event services. With standard fieldbus user layer function block (FB) and device description functions. Provides 32 kinds of standard function blocks, on-site installation to use these function blocks to complete control strategy. As the device features including a description of device communication describes all the information needed, and nothing to do with the master station, thus making the field devices to achieve real interoperability.

10 Type10 PROFI net Fieldbus

PNO organization in August 2001 issued a PROFInet specification. PROFInet to factory automation and enterprise information management, organically integrated IT technology, while fully retaining the existing open Profibus.

PROFInet field bus architecture shown in Figure 10, seen from the figure, the program supports an open, object-oriented communication, such communication based on the widespread use of Ethernet TCP / IP based on the optimization of the communication mechanism can meet the real-time communication requirements. Object-based applications, DCOM communication protocol through the protocol standard to establish. Expressed in the form of an object under the object agreement PROFInet component of its automated data exchange. Automation object that is COM object as a PDU in the form of DCOM protocol defines the communication bus. Connection object activity control (ACCO) ensure that each connected device configuration the relationship established between the communication and data exchange. Transient in nature by the event-controlled, ACCO is also responsible for fault recovery, including the quality of code and Shi Jian marking the transfer, Lian Jie's Jian Shi, connection is lost again after the connection of the establishment of Yijixianghu Test and Diagnosis.

Profibus can be through a proxy server (Proxy) is easily achieved with other field bus systems integration, in the program, through a proxy server be used with universal Profibus network connection to industrial Ethernet; through Ethernet TCP / IP access Profibus ???Proxy use by the Microsoft DCOM remote procedure calls and for processing.

PROFInet provide engineering design tools and manufacturer-specific programming and configuration software, use this tool can programming software development from the controller device to create based on COM automation object, such tools will be used for automatic configuration based on PROFInet system, using this independent of the manufacturer's object and link editor can reduce development time by 15%.

Conclusion

Of 10 different types of field bus communication protocol used. Type1 way with LAS and Publisher / Subscriber model; Type2 ControlNet use CTDMA methods and Producer / Consumer model, Ethernet / IP using Ethernet TCP / IP protocol; Type3 is the Token Ring and master / slave mode; Type4 communication using virtual token transfer mode; Type5 using CSMA / CD mode and Ethernet TCP / IP protocol; Type6 use TDMA multiple access methods; Type7 use the bus adjudication; Type8 agreement with the whole frame; Type9 way with LAS and Publisher / Subscriber model; Type10 use Ethernet TCP / IP protocol.

As can be seen from the above discussion, ten types of field bus architecture and communication protocol are not the same, but Ethernet TCP / IP Industrial Ethernet technology for high-speed Fieldbus H2 basic consensus, Ethernet / IP, FF HSE and PROFInet Industrial Ethernet technology in fact has become the international standard.

It is understood, IEC61158 standard of the maintenance period for the December 31, 2007, that does not increase before the new field bus, within the current standard field bus will not make changes. Thus, field bus system architecture and pattern has been basically established, industrial Ethernet and fieldbus systems can be defined in clear relationship between them in Table 1.

Table lists the current industrial Ethernet technology, four major competitors, FF HSE, EtherNet / IP and PROFInet the field level has its own bus, this pattern will not change. Phoenix Contacts Company Type8 INTERBUS IDA Industrial Ethernet technology used in developed rapidly, and extended to the field of industrial Ethernet I / O level, and Modbus TCP / IP protocol has been submitted to the International Internet Engineering Task Force (IETF), hope that this agreement will become the industry standard Internet protocols. In order to accelerate this work, MODBUS IDA organizations and organizations in the end of October 2003 announced the merger. China is also carrying out development work on industrial Ethernet, Zhejiang University in the development of EPA Control Technology Co., Ltd. Industrial Ethernet has been extended to the field level, and successful trial in the chemical plant.

Fieldbus long debate people gradually recognized that digital technology of Tong Yi completely different from the simulation technology, field bus control system unification of the road should be unified Chongfenxishou Internet technology Shixian successful experience in the market-oriented, innovative, ??? one with interoperability of industrial Ethernet networks for industrial automation eventually create a unified information platform.

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