From the initial single-board machine to PLC, PC, and then to the birth of PAC comprehensive control products that combine the advantages of PLC and PC, the form of industrial controllers has become increasingly rich over the course of history. However, due to their different characteristics, there exists a certain replacement relationship among different controllers: PC poses challenges to PLC, and the new PAC is impacting the market.
“In the long term, control products based on PLC/open, PC-base programming, and PAC will coexist for a long time,” said Yang Li, Director of Intelligent Application Technology at Leisai.
Siemens and the Past and Present of PLC
The birth of PLC has a significant “connection” with automobile production.
In 1969, Digital Equipment Corporation in the United States developed the first programmable logic controller—PDP14. It was successfully tested on the production line of General Motors, replacing the relay control system on the production line and opening a new era of industrial control.
The early programmable controllers were designed to replace relay-contactor control systems, used for switching control, with logical operations, timing, counting, and other sequential control functions, hence the name programmable logic controller PLC.
In 1971, Japan began producing programmable controllers, followed by Germany, England, France, and other countries developing suitable programmable controllers for their own countries and promoting their use.
In 1973, Siemens in Germany developed Europe’s first programmable logic controller, model SIMA TICS4.
In 1974, China also began developing and producing programmable controllers.
In the early 1970s, microprocessors appeared. People quickly introduced them into programmable logic controllers, adding functions such as computation, data transfer, and processing, completing the true characteristics of a computer-based industrial control device. At this time, programmable logic controllers were a product of the combination of microcomputer technology and relay conventional control concepts.
PLC entered a practical development stage.
Computer technology has been fully introduced into PLC, leading to a leap in its functions. Higher computing speed, ultra-small size, more reliable industrial anti-interference design, analog computation, PID functions, and extremely high cost-performance ratio have established its position in modern industry.
In the early 1980s, PLC had been widely applied in advanced industrial countries. The number of countries producing PLC was increasing, and production volume was rising. This marked that PLC had entered a mature stage.
From the 1980s to the mid-1990s, PLC experienced the fastest development period, with an annual growth rate consistently maintained at 30-40%. By the end of the 1980s, PLC technology had matured and expanded from switching logic control to computer numerical control (CNC) and other fields, gradually entering the process control field, and in some applications, it replaced the dominant DCS systems in the process control field.
At that time, PLC had new breakthroughs in processing speed, control functions, and communication capabilities, and developed towards the integration of electrical control, instrument control, and computer control, with continuously improving cost-performance ratios, becoming one of the pillars of industrial automation.
By this time, the functions of programmable controllers were no longer limited to logical operations, and they had capabilities for continuous analog processing, high-speed counting, remote input and output, and network communication.
At the end of the 20th century, the development characteristics of programmable logic controllers required them to adapt more to modern industry. During this period, large and ultra-small machines were invented, various special function units were created, and various human-machine interface units and communication units were produced, making it easier to match industrial control devices that use programmable logic controllers.
As one of the earliest companies to develop PLC, Siemens has a very high market share of PLC in China. This company, which regards “innovation” as its principle, has continuously iterated PLC products over the past few decades, from the initial SIMATIC S3 to SIMATIC S5, S5-U series PLC, and then to S7 series, PCS7 series.
Currently, S3 and S5 series PLC have gradually exited the market and stopped production, while the S7 series PLC has developed into the control core of Siemens’ automation system, and the TDC system continues to use the SIMADYN D technology core, which is a further upgrade of the S7 series products, making it the most advanced and powerful programmable controller in Siemens’ automation system.
With high stability and reliability, PLC has become a competitive control tool in the field of automation and is still one of the mainstream control tools. However, due to the closed architecture of PLC, the hardware systems of various PLC manufacturers are incompatible with each other, and the programming languages and instruction systems vary, leading to low openness.
In addition to Siemens, the PLC camp also includes Rockwell and ABB, while domestic manufacturers with good performance include Wuxi Xinjie, Beijing Heli Group, Delta, Zhejiang University Zhongkong Group, Hexin Automation, and Kewi.
Beckhoff and the Development History of PC Control Technology
With the rapid changes in the market and the development requirements of intelligent manufacturing, customers have raised more and more demands for control systems, including requirements for digitalization and informatization. In addition to focusing on high cost-performance ratios, there is also an increasing focus on system flexibility and openness.
Moreover, control systems need to integrate more functions onto one platform to reduce costs and improve efficiency, such as integrating image processing, status monitoring, machine learning, robot control, and other functions. Control systems also need to be compatible with different sensors and actuators to better adapt to customer requirements for performance, price, and service.
In 1986, Beckhoff launched the first PC-based device controller; in 1988, it launched the PC-based soft PLC/NC (DOS), opening a new era of motion control.
2019 marks the 33rd anniversary of Beckhoff’s introduction of PC-based control technology and the 18th year since Beckhoff entered China. The PC controllers, continuously developed EtherCAT real-time Ethernet communication technology, and TwinCAT software platform constitute the “three primary colors” of Beckhoff’s PC control system.
In 2018, although the automation market showed a significant slowdown in growth, Beckhoff China still achieved satisfactory results, with overall business achieving an 8% growth, and sales reaching a historic high of 1.03 billion RMB. It is reported that Beckhoff China’s actual growth rate in the fields of metal processing, photovoltaics, semiconductors, and electronics manufacturing reached 32%.
Beckhoff’s performance in results fully proves the strong vitality of PC-based control technology.
PC-based controllers are applied in many industries within the motion control field, such as robotics, semiconductors, packaging machinery, and EMS. With the increasing demand for industrial robots in the automotive and semiconductor industries, as well as the use of industrial robots in emerging industries such as ceramics and sanitary ware and pharmaceuticals, it has stimulated the rapid development of PC-based motion controllers in the robotics field.
In addition, Cartesian robots and domestic brands of multi-joint robots with simple functions and low prices are increasingly chosen by manufacturers for their cost-effectiveness.
In recent years, semiconductor processing and packaging testing manufacturers have rapidly built factories in China, and domestic semiconductor equipment sales revenue has maintained an adjusted growth of 15-20%. Among the motion controllers used in these devices, 50% are PC-based motion controllers.
Moreover, the packaging machinery industry is gradually adding machine vision functions, leading to a gradual increase in the demand for PC-based motion control.
Industry insiders point out that in the future, the application fields of PC-based motion controllers will further expand, and part of the PLC market will shift to the PC-based market.
For this reason, Liang Liqiang, Managing Director of Beckhoff China, stated that Beckhoff China will continue to promote and advocate open control systems based on PC, focusing on developing strategic emerging industries, including lithium battery equipment, electronic manufacturing, semiconductors, warehousing and logistics industries, and the high-end equipment manufacturing industry that the state is focusing on developing.
The development of PC-based technology undoubtedly poses a challenge to PLC. Previously, some predicted that PLC would gradually exit the stage of industrial automation history. However, in the past 10 years, the performance of ultra-small and small PLC has greatly improved, and production has significantly increased.
In the PC-based controller camp, in addition to Advantech, North China Industrial Control, and Yanzheng, currently in the PC-based motion control product market, domestic manufacturers such as Godo, Zhongweixing, and Leisai dominate the motion control card segment.
In the embedded controller and soft PLC segments, foreign manufacturers represented by Beckhoff, B&R, and CODESYS still hold a major market share. Of course, there are also some domestic companies based on PC technology, including Huacheng Industrial Control, Nabote, and Runtong Intelligent.
PAC: A Gimmick or a Trend?
Currently, many modern industrial applications require more functional demands, such as network connectivity, device interoperability, and enterprise data integration, which far exceed the capabilities that traditional PLC based on discrete logic control can provide. To achieve these functions based on PLC, it is necessary to use separate processors, gateways, converters, run on independent PC software middleware, and specialized software at the enterprise system level for system integration.
At the beginning of automation applications, PC-based technology was highly questioned by the PLC camp, and to this day, there are still related doubts in the market, mainly concerning stability, reliability, and the instability of programming design environments. Therefore, some engineers use PLC in combination with PC, although this is more troublesome for system integration.
To solve the integration problem of PLC and PC-based, the American research institution ARC proposed the PAC (Programmable Automation Controller) architecture, which integrates PLC and PC-based technologies. At the PC level, it will apply embedded technology extensively and have the ability to define hardware using software.
Proponents believe that the value of PAC lies in the integration of all components according to the principle of being the most flexible, convenient, and cost-effective, thereby reducing the lifecycle costs of user devices and improving the return on investment of assets, leading to a decrease in the total cost for asset owners.
Of course, there are also viewpoints that PAC still belongs to PC-based products, just packaged differently.
However, from the overall market perspective, PAC has indeed gradually taken shape, with major manufacturers, including Siemens, launching products, and domestic companies like Advantech also introducing a new generation of PAC controller, the APAX-5000 series.
They believe that in the future, embedded technology will be widely used in PAC, becoming one of the important technologies in automation systems.
Among users and system integrators, there are also doubts about PAC: PAC is more expensive than PLC, has lower reliability, and poorer expandability. Some people believe that PAC does not truly address any urgent or potential market demand, hence it may not gain widespread acceptance.
Some opponents argue that the development trends of PAC technology, such as unified multi-professional development platforms and communication technologies, will also exert beneficial influences on the technological development of PLC.
It is worth mentioning that, in addition to the aforementioned PLC, PC-based, and PAC, specialized controllers for robotics applications have become the focus of layout for many domestic manufacturers, especially for enterprises like Estun, Huazhong CNC, and Peitian Robotics, which focus on R&D of robotic bodies.
On December 11-13, the “Li Yuan Heng • 2019 High-tech Robotics Annual Conference” hosted by Gaogong Robotics will be held at the Hyatt Hotel at Shenzhen Airport, with the theme of “Ecological Interconnection • Breaking Through Adversity.”
At that time, controller companies represented by Advantech, Delta, and Huacheng Industrial Control will be giving relevant speeches and discussions at the conference, bringing you more insights into controller technology trends and application experiences. Stay tuned!
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