With the development of computer technology, communication technology, and control technology, fieldbus technology has been widely applied in industrial control systems, and has also begun to be used in the textile industry. This article introduces the basic principles of fieldbus, compares several existing fieldbuses, and, based on an analysis and summary of the new characteristics of the development of digital textile production control systems, introduces the current situation of fieldbus application in the domestic and international textile industries.
1 Introduction
With the continuous and rapid development of my country's textile industry, modern textile technology will be dominated by electronic information technology and characterized by intelligent production [1]. At present, the development of domestic textile machinery and equipment control systems focuses on realizing the automation of textile process performance of single equipment, enclosing the advanced functions of the machine in a single system, while ignoring the network structure of the system. As a result, the structure of the machine (especially its control system) will become more and more complex, making the machine an "island" in the automation system of textile enterprises. Since the 1990s, fieldbus technology and control systems based on this technology have attracted great attention at home and abroad, becoming a hot spot in the development of automation technology worldwide. It integrates microprocessor technology, network technology, communication technology and automatic control technology, and puts the microprocessor into the field automatic control equipment, so that the equipment has the ability of digital calculation and digital communication. It not only improves the accuracy of signal measurement, control and transmission, but also creates conditions for realizing its remote transmission.
In the process of the textile industry's transformation from traditional to modern industry, fieldbus-based control technology has provided opportunities for the development of textile industry control systems towards decentralization, networking, and intelligence. This paper introduces the basic principles of fieldbus, compares the characteristics and application scenarios of several commonly used fieldbuses, and builds a framework model of a digital textile production system based on fieldbus control technology.
2. Basic Principles of Fieldbus
Fieldbus is the intersection of the development of 3C (Computer, Communication, Control) technologies, as well as the convergence of process control technology, automation instrumentation technology, and computer network technology. It is a concentrated manifestation of the development of information technology and network technology in the control field and an inevitable result of the extension of information technology and network technology to the field.
According to the standards of the International Electrotechnical Commission (IEC) and the Fieldbus Foundation (FF), fieldbus is a digital, bidirectional, multi-branch communication network that connects intelligent field devices and automation systems [2]. Fieldbus technology incorporates dedicated microprocessors into traditional measurement and control instruments, enabling them to have digital computing and digital communication capabilities, and to become network nodes capable of independently undertaking certain detection, control, and communication tasks. A network system is formed by connecting multiple measurement and control instruments, computers, etc. as nodes through ordinary twisted-pair cables; using open and standardized communication protocols, data transmission and information sharing are realized between multiple microcomputerized measurement and control devices located at the production control site, as well as between field instruments and remote computers used for monitoring and management, forming various automatic control systems that meet actual needs.
Fieldbus is primarily designed for process control. In addition to transmitting direct information such as digital and analog signals, it can also transmit control information. The data unit exchanged on the network is a frame. Compared with distributed control systems (DCS), fieldbus control systems (FCS) have advantages such as higher reliability, better security, interchangeability and interoperability, openness, and decentralization.
In summary, fieldbus is a real-time control communication network that interconnects the lowest-level field controllers and field intelligent instruments in automation. It follows all or part of the communication protocols of the ISO/OSI Open Systems Interconnection Reference Model.
3. Several common fieldbus technologies
Since the 1980s, major international companies have successively launched several industrial fieldbuses and field communication protocols. Currently popular protocols include FF (Fieldbus Foundation), Profibus (Process Fieldbus), CAN (Controller Area Network), LonWorks (Local Operation Network), and WorldFIP (Factory Instrumentation Protocol). Their main technical differences and applicable scenarios are as follows:
3.1FF Fieldbus
The Foundation Fieldbus (FF) is based on the ISO/OSI Open Systems Interconnection model, taking its physical layer, data link layer, and application layer as the corresponding layers of the FF communication model, and adding a user layer on top of the application layer. FF offers two communication rates: low-speed H1 and high-speed H2. H1 has a transmission rate of 1.25 kbit/s, a communication distance of up to 1900 m (extended with repeaters), supports bus power supply, and is intrinsically safe for explosion-proof environments. H2 has transmission rates of 1 Mbps and 2.5 kbit/ s , with communication distances of 750 m and 500 m respectively. The physical transmission medium supports twisted-pair cable, fiber optic cable, and wireless transmission. The protocol conforms to the IEC 11582 standard, and the transmitted signals use Manchester encoding. It is mainly used in process automation fields, such as chemical, power, oilfield, and wastewater treatment.
3.2 Profibus Fieldbus
The Profibus series consists of three compatible parts: Profibus-DP, Profibus-FMS, and Profibus-PA. Profibus adopts the physical layer and data link layer of the OSI model, which form a subset of its standard part one. Profibus has a transmission rate of 9.6 kbit/s to 12 Mbit/s, with a maximum transmission distance of 100m at 12 Mbit/s and 400m at 1.5 Mbit/s, which can be extended to 10km using repeaters. Its transmission medium can be twisted-pair cable or optical fiber. Main application areas include: DP type is suitable for processing automation applications, such as pharmaceuticals, cement, food, power, power generation, and power transmission and distribution; FMS is suitable for general manufacturing automation such as textiles, building automation, programmable logic controllers, and low-voltage switchgear; PA type is a bus type used for process automation. 3.3 CAN Fieldbus
CAN network design adopts a three-layer architecture model conforming to the ISO/OSI network standard: physical layer, data link layer, and application layer. The physical and data link layer functions are performed by the CAN interface device, while the application layer functions are performed by the processor. Communication features outstanding reliability, real-time performance, and flexibility; it uses a short frame structure, resulting in short transmission time and strong interference resistance; nodes are assigned different priorities to meet varying real-time requirements. Its transmission media can include twisted-pair cable, coaxial cable, or optical fiber, with a maximum communication rate of 1 Mbit/s (40m) and a maximum direct transmission distance of 10km (5kbit/s). Major application areas include: automotive manufacturing, robotics, hydraulic systems, distributed I/O, machine tools, and medical devices.
3.4 Lonworks Fieldbus
LonWorks employs a 7-layer protocol architecture similar to the OSI reference model. The core of LonWorks technology is the Neuron chip, which integrates communication and control functions. The Neuron chip implements the complete LonTalk communication protocol for LonWorks, enabling peer-to-peer communication between nodes. LonWorks communication rates range from 78 Kbit/s to 1.25 Mbit/s, supporting various physical media including twisted-pair cable, fiber optic cable, coaxial cable, power line carrier, and wireless communication; it also supports multiple topologies, allowing for flexible networking.
Its main application areas include industrial control, building automation, data acquisition, SCADA systems, etc., and it has superior performance in building distributed monitoring networks.
3.5 WorldFIP Fieldbus
The WorldFIP fieldbus architecture is divided into three levels: process, control, and monitoring. Its protocol consists of a physical layer, a data link layer, and an application layer. Communication rates include 31.25 Kbit/s, 1 Mbit/s, 2.5 Mbit/s, and 25 Mbit/s. Shielded twisted-pair cable and fiber optic cable are used as transmission media. It can meet various user needs and is suitable for centralized, distributed, and master/slave application structures. A single WorldFIP bus can meet the needs of process control, factory manufacturing, and various drive systems. Major application areas include: power industry, railway, transportation, industrial control, and building systems.
4 Textile Production Control System Based on Fieldbus Technology
The informatization of the textile industry will be a key focus and priority for textile factories in the coming years, and a digitalized textile production system is an indispensable foundation. It will comprehensively improve the management level of textile factories and have a direct and significant impact on the advancement of their technology, quality, economy, and services.
Digitalized textile machinery employs modern, advanced control technologies: CPU-based controllers, new drive technologies based on power electronics, and network and high-speed data communication technologies represented by fieldbus technology. This enables real-time, accurate data acquisition and high-speed transmission, improves distributed, on-site, and anti-interference performance, and achieves automation and intelligence in the production process. It completes the integration of textile machinery with modern advanced control technologies, laying a solid foundation for the informatization of textile enterprises from the equipment level.
According to the network connection structure, enterprise network systems are generally divided into four layers: control layer, monitoring layer, management layer, and information layer. A textile production information system based on fieldbus technology is shown in Figure 1.
The fieldbus control layer is the source of various production information. Controllers of various cotton spinning, weaving, and dyeing machinery, as long as they have fieldbus communication interfaces, can transmit machine operation data to the monitoring system in real time through appropriate programming. The fieldbus monitoring layer completes workshop-level equipment detection and control. Using configuration software programming and fieldbus networks, it integrates the control systems of various individual machines within the workshop, enabling monitoring of the production status, output, and efficiency of all equipment in the workshop through a clear and user-friendly human-machine interface. It also allows for unified setting of equipment process parameters, fault alarms, parameter recording, display of historical trends and real-time curves, and generation and printing of various production reports. The management layer is the factory-level information management system. Control systems can establish databases through various buses and industrial networks according to user needs, process and categorize data, and send it to various management departments, enabling data querying, statistics, analysis, and reporting. The fieldbus information layer integrates control processes, information management, and communication networks, achieving data sharing. Relevant personnel can log in to the web server to monitor the operation of equipment on the production site according to their respective permissions.
5 Application Cases
Due to its unparalleled advantages in reliability, openness, economy, and fully digital transmission, fieldbus technology meets the needs of modern textile industry for high-quality, low-cost, small-batch, multi-variety, rapid response, high-efficiency and low-consumption, and clean production. Currently, fieldbus technology has begun to be widely used in textile machinery and equipment such as spinning, chemical fiber, weaving, knitting, dyeing and finishing, and garment manufacturing to simplify the composition structure of production systems, form flexible production systems, ensure product quality, reduce production costs, and promote computer-integrated production in the textile industry.
In foreign-made equipment for chemical fiber, weaving, and dyeing and finishing that uses fieldbus technology, modular field devices of different manufacturers' standards are distributed in various parts of the machine. They are then assembled into a dedicated system using control network integration technology. This simplifies the system hardware design and reduces wiring costs.
For example, the Swiss SulzeTextile G6300 rapier loom uses servo motors for weft insertion, warp feeding, take-up, and selvedge weaving. The main controller is a 32-bit multiprocessor architecture. All field devices in the loom are connected via a CAN fieldbus to form a control network. Fabric specification weaving conditions and control data conversion can be remotely controlled or set on-site. The German THEN AIRFLOWAFT piece dyeing machine uses the THEN-DYNET (TDN) control system, which employs a LonWorks fieldbus control network architecture. Actuators such as airflow control valves, inlet and outlet water valves, and heat exchanger control valves, as well as sensors for dye liquor temperature and fabric speed, are all autonomous field devices connected to the host PLC controller as nodes in the overall control network.
my country began researching fieldbus technology in 1993, and in 1996, the research and development of fieldbus technology and products were officially listed as a key national science and technology project during the Ninth Five-Year Plan period. By 1998, some incomplete fieldbus OEM new products had been launched. Domestic textile machinery manufacturers seized the opportunity to actively introduce advanced fieldbus technology and, combined with the functional characteristics of various textile machinery, focused on the system integration of fieldbus products. For example, the four-motor driven roving frame developed by Shanghai No. 2 Textile Machinery Co., Ltd. adopted the CAN bus. Large-capacity polyester spinning and post-processing production lines all adopted the Profibus bus. Shanghai Pacific Electromechanical Group, in developing a complete set of equipment for producing 30,000 tons of polyester staple fiber per year, developed a fieldbus-based control system, reaching the advanced level of similar international products.
6. Conclusion
Fieldbus technology is one of the hottest developments in the field of automation today. Its emergence has revolutionized the traditional control system structure, propelling automation systems towards intelligence, digitalization, informatization, networking, and decentralization, forming a new type of network-integrated, fully distributed control system—the fieldbus control system. As a development direction for industrial automation, fieldbus control systems offer excellent opportunities for the automation field of my country's textile industry. With the widespread use of fieldbus products, the absorption of R&D costs, and the reduction of production costs, fieldbus products will be extensively applied to textile industry automation systems, and fieldbus system technology will be widely used and develop significantly in textile automation.
