The future view of fieldbus

Modern production control systems have two of the most significant trends, one is becoming more and more intelligent, and the other is becoming more and more miniaturized and decentralized in structure. The reason for the previous trend is the diversified demand in the product market, forcing the traditional production model to move towards a personalized manufacturing model; the latter trend stems from the advancement of microelectronics and information technology. In this development and change, a very important technology is fieldbus technology. If modern manufacturing control systems are increasingly dependent on the development of fieldbus technology, it cannot be overstated.
The foundation of fieldbus technology is serial communication technology and network technology. Since Intel introduced its serial bus BitBus for low-speed I/O in the 1980s, this low-cost, flexible and convenient means of communication has become more and more widely used, especially in the control and automation of industrial production. . After years of evolution, a variety of fieldbuses have been formed for different application fields.
The emergence of fieldbus has greatly changed the face of industrial control systems, especially the control equipment directly related to the production site. In the past, the control system was equipped with various types of instruments, including sensors and actuators. Most of these devices were displayed locally and operated locally at an early stage. This makes the control and management of the entire production unit quite difficult and complicated. This situation has changed a lot since the appearance of the electric unit combination meter. Since the field instrument can transmit the on-site status to the centralized control room through the transmission of electrical signals, the operator can realize centralized control and management of the production device. The further development of the electric unit combination meter is a new generation of intelligent instruments that are intelligent and digital. The biggest feature of smart meters is that their internal processing is digitized, and their external communication is also through digital communication rather than electrical signals. Its superiority is reflected in the function. Field instruments can perform much more complex operations and processing than traditional instruments, enabling more precise control. More importantly, in addition to the control, the field instrument also has a certain degree of management functions, which ensures that the integration of the control and management of the production device is guaranteed from the field. The fieldbus undertakes the communication connection between the smart meter and the centralized control and management center and between the smart meters. It is the field bus that constitutes a complete production control management system.
How to develop the field bus in the future is a common concern. From the current situation, there is still considerable room for development in fieldbus technology, and its application is still in its infancy, far from reaching the popularization stage. In order to promote the wide application of fieldbus, what problems do we have to pay attention to? It can be summarized as the following five aspects.
First, the cost
As a field-level network device, its usage is very large, so the fieldbus is a price-sensitive product. Unlike traditional instruments that simply transmit analog signals, fieldbuses transmit digital signals. Fieldbus-related devices include hubs, repeaters, and switches in addition to wires. Network devices such as Gateway, Bridge, and Router. The unit price and usage of these devices will directly affect the cost of the final fieldbus system.
Second, reliability
Since the installation conditions of the fieldbus equipment are generally not very good, this puts high requirements on the operation of the fieldbus equipment, such as resistance to harsh environment, anti-electromagnetic interference capability, anti-vibration capability and resistance to power fluctuations, lightning strikes, Anti-surge current capability, etc., all need to be very strict in all aspects of product design, installation, protection, etc., in order to ensure the reliable operation of the equipment. In addition, because the installation location of the fieldbus devices is very scattered, it is very inconvenient to check and maintain them, and the number is large, so it is very important to achieve low maintenance or even maintenance-free equipment. If the reliability of the fieldbus device cannot reach a high level, the maintenance cost of the system will be high, and it will remain high during the long-term operation, which is very unfavorable for the application of the fieldbus.
Third, technical difficulty
For the need to use fieldbus on a large scale, the technical complexity should be minimized, and there may be different opinions on this. Fieldbus is a very promising technology. With the rapid development of microelectronics, network technology and software technology, the potential of fieldbus will continue to play. Naturally, for technology developers, they want to give more and more features to this new technology, making it more powerful. However, from an application point of view, the primary goal for the fieldbus is to use it over a large area, and the complexity of the function hinders its rapid and widespread promotion. For plants using fieldbus, the previous instrument shop will be transformed into the department of installation, use, operation and maintenance of the fieldbus. Faced with such a new device that differs from traditional instruments from basic technology, it requires a longer period of training, learning and adaptation. Especially in the early stage of fieldbus application, the instrumentation department of the factory will face two completely different technologies and products. Whether it can be smoothly transferred to the new system has a great relationship with the ease of use of new technologies. If the products of the new technology are too complicated, then the factory has to rely on the supplier for a long time, which is not a small cost. Moreover, from the general situation, it is more difficult to use the maintenance and diagnosis of the technically complicated products, so the possibility of outage during the operation is relatively large.
Fourth, standardization
The fewer types of fieldbus products, the better, because the more standardized products, the more large-scale applications, the large-scale production, the better quality assurance and lower costs. However, the current situation is that the variety of fieldbus products is quite large, which has caused great difficulties in the widespread adoption of this new technology. There are many reasons for this, but it is the technology itself. Fieldbus technology is based on networking and software, which makes its functionality unprecedented and natural, and its application coverage is unprecedented. This is in contrast to the traditional instrumentation. If the range covered by traditional meters is limited to on-site measurement and control, the fieldbus coverage extends to the complete control system. In the field of industrial production, because the production objectives, methods, processes and control methods are various and impossible to unify, the field bus for the complete control system also produces a variety of products. This is naturally formed and no one can change it. This has become a paradox: a powerful fieldbus should have a wide application market, but for a wide range of market applications, it must form a variety and complexity of products, which has created obstacles to its widespread application. How to solve this paradox is a big problem facing the field bus. Because the current intelligent demand for production and manufacturing is getting higher and higher, smart meters and fieldbus cannot be intelligently manufactured. Not only do large enterprises need to achieve smart manufacturing, but SMEs also need to move toward smart manufacturing. These are calling for standardized, highly reliable, low-cost, easy-to-use fieldbus systems. The rapidly emerging industrial Ethernet technology in recent years is gradually approaching such a goal. As a high-performance digital network, Industrial Ethernet provides standard network equipment, as well as a variety of transmission media. The underlying protocol is simple and adaptable, enough to meet the needs of all walks of life. The various profiles formed on the basis of this provide rich functions for different industry applications, thus meeting the different needs of different industries for control functions.
Five, security
The security issue has only begun to attract people's attention in recent years. The security mentioned here mainly refers to information security. Since the general trend of the control system is to become networked, the problem of information security is becoming more and more serious and must be highly valued. Although we cannot rely solely on technical means to ensure information security, perfect protection measures are necessary and necessary for networked systems.