Network technology enables high-speed, secure, and reliable data transmission across the entire plant. PLCs , with enhanced diagnostic and communication capabilities, provide intelligent, low-maintenance systems that can bring significant benefits to the factory. Manufacturers can now improve accuracy, deliver faster production speeds, reduce errors, and save on material and labor costs.
With the widespread use of human-machine interaction in factories, the days when labor acted as the brain and driving force in the manufacturing process are long gone. A prime example is the PLC , which has been a mainstay in various industrial sectors, including automation and manufacturing, for many years. By interfaced with virtually any equipment—from sensors and equipment protection to motion control and advanced identification devices—PLCs ensure smooth equipment operation. Leveraging the flexibility offered by PLCs, equipment manufacturers can manage multiple machines simultaneously, thereby further integrating process automation equipment, improving product quality, and reducing operating costs.
The benefits of using PLCs are well-known. Enhanced control capabilities are attributed to the efficiency improvements contributed by PLCs and the underlying support of Industrial Ethernet. Furthermore, these technologies enable a seamless and beneficial human-machine interaction. Industrial Ethernet, comprised of a wide variety of communication protocols with defined functions, provides an effective alternative for dedicated automation systems.
With their advanced performance, complex functions, and simplified installation, PLCs are the cornerstone of modern manufacturing industries. However, to effectively utilize these devices, users must understand the critical role of the network and consider individual needs to provide optimal solutions. Together, they constitute a unified infrastructure: a network extending from the management level all the way to the shop floor, possessing inherent scalability to continuously meet evolving industrial demands.
Expanding PLC Functionality via Network
While PLCs opened the door to factory-wide visual communication, it was the integration of network devices that truly elevated production visualization and control to a new level, combining real-time networking, visualization technologies, control, and communication capabilities. As networks continue to evolve, monitoring and control functions are being provided in many previously impossible areas. The combination of fieldbus to Ethernet bus conversion enables the development of enterprise-wide control networks. The convergence of network capabilities and PLCs allows users to reduce the load on the main processor of distributed control systems, placing control layer devices closer to the application. Furthermore, through integration with distributed I/O, manufacturers can streamline data acquisition, communication, and plant-wide connectivity, thereby reducing overall operating costs.
Processing power, data storage capacity, and communication capabilities make modern PLCs an ideal solution for providing intelligent and powerful field-level application control.
Networking: For a PLC to function as a network tool, users must have the necessary bandwidth to support the operation of real-time industrial Ethernet. As connectivity and communication demands continue to increase, PLCs must also be upgraded to support multiple network technologies. While no single industrial network can be used for all advanced I/O solutions, by using multiple network protocols, PLCs can connect the enterprise layer to the factory layer as needed. Because network protocols expand functionality, PLCs become essential devices for driving and supporting these new features.
To ensure the continuous operation of these integrated systems, maintaining these industrial automation networks is crucial. A stable network is paramount. Therefore, maintaining network availability is essential. This requires the system to support the necessary bandwidth, high data transfer rates to meet application demands, and data protection during maintenance operations and rapid recovery from connection failures.
Like speed and availability, redundancy is crucial for performance and reliability. Extended unplanned downtime can pose a potential threat to factory production capacity. However, redundancy technologies not only provide millisecond-level network recovery but also significantly reduce operating costs.
Distributed control: Distributed control technology allows different parts of an automation system to be decentralized throughout the system. This means that certain parts of the system can be controlled by different controllers located close to the controlled object. Multiple different form factors can be used for a wide range of application needs. Furthermore, by appropriately distributing I/O data throughout the application (within a cabinet or on a machine), manufacturers can reduce the number of necessary components, thereby reducing the size of automation and control equipment.
Distributed control offers inherent scalability, allowing users to flexibly utilize modular designs and precisely configure I/O as needed, enabling rapid and cost-effective system expansion in the future. Distributed intelligent systems not only do not increase the load on the PLC but can also be expanded to control automation applications using the same PLC, allowing the system to adapt to future functional requirements. This means users can expand the system by increasing size and functionality while maintaining the standardization of the PLC system.
During load offloading, transferring some control functions from the main controller (PLC or PC control) to distributed I/O (located within the machine or rack) can reduce network load. This is because with distributed I/O, the main controller does not need to request input status or trigger outputs from remote I/O. Distributed I/O systems with control/programmable functions can handle specific tasks, regulate and monitor communications, and send status data to the main controller.
By allowing remote I/O configuration, manufacturers can achieve high levels of connectivity (even over a wide area) with fewer I/O points, providing cost-effective control solutions for a wide range of industries and applications. Large factories require extensive monitoring and control capabilities, and setting up controllers at every location is neither feasible nor economical. This requires lengthy installation processes and expensive costs, including long-distance cabling to connect I/O points via hardwiring. For example, remote I/O systems can be used when acquiring data from distant factories or facilities. Information such as cycle times, point counts, time, or events is sent back to the PLC for maintenance and management reporting. Furthermore, hardwiring increases the likelihood of errors, such as wiring mistakes requiring lengthy downtime for correction.
Advanced I/O capabilities: Network technology has long since moved beyond standard digital inputs, digital outputs, analog inputs, and analog outputs. For example, advanced I/O capabilities include RFID technology, SSID and serial inputs for motion control, data logs, barcodes, and 2D matrix identification systems. Smarter, more advanced I/O systems generate more data, which the PLC must be able to process.
Typical factory environments require more compact control systems to manage production processes, which necessitates more than just discrete I/O. PLCs are equipped with advanced I/O, such as analog signal processing, temperature control, and RFID, all of which consume more bandwidth.
For example, PROFINET uses three different communication channels to exchange data with PLCs and other devices. The standard TCP/IP channel is used for parametric configuration and non-periodic read/write operations. Real-time (RT) communication bypasses the standard TCP/IP interface, accelerating data exchange with the PLC system. The third is a high-speed synchronous real-time channel for motion control.
Integrating network and PLC on site
Remote I/O: The oil and gas industry deals with hazardous industrial environments, demanding high accuracy and reliability. For any application, not only reliable performance is required, but it must also adapt to constantly changing needs and increasing commands. Traditional control solutions are inadequate, necessitating modular solutions that allow for decoupling and relocation. A fundamental requirement for the oil and gas industry is the use of innovative connectivity solutions that enable ultra-long-distance communication without sacrificing performance or being less susceptible to environmental influences. These requirements necessitate a reliable integration of control devices such as PLCs and network protocols.
Designing factory equipment distributed over a wide area presents a challenge for these plants. This requires a network to handle a large volume of signals while minimizing wiring space and preserving necessary maintenance space. Distributed I/O systems offer an effective solution to complex problems by allowing for rapid disconnection of wiring systems in hazardous areas. Easily configurable systems and process applications provide remote I/O capabilities. A single Ethernet cable can handle a large volume of data communication, sending up to 150 remote signals back to the PLC from different areas of the factory.
By utilizing a sophisticated wiring system as the terminal for field process instruments, these signals are amplified at the junction box, improving their efficiency. Furthermore, by using shielded twisted-pair cables to transmit signals from the junction box to the PLC cabinet, and connecting the junction box and instruments with armored shielded twisted-pair cables, it is no longer necessary to connect all cables separately to the PLC. Instead, the previously used 8-core cables have been consolidated into a single cable. Due to the smaller size of the cable tray, the size of the PLC cabinet is also reduced. This results in additional cost savings.
Furthermore, to meet the specific needs of the oil and gas market and its hazardous areas, these devices must be installed correctly. Options provided include certified network protocols for Hazard Group 2/Zone 2, enhanced temperature signals, 4~20mA and discrete signals, and high-speed transmission of these signals to the PLC.
Enhanced Automation: Coal production companies require extensive transportation systems throughout the plant area to move coal from storage sites to mills. These systems must be highly reliable at all times to maximize plant productivity. Thus, automation becomes an inevitable choice, but this necessitates the installation, management, and maintenance of numerous sensors and actuators throughout the plant.
To meet these specific needs, using modern Fieldbus systems to transmit signals from PLCs and sensors/actuators provides the necessary level of automation, control, and continuity. For devices with modular designs and robust protection features, proper use of Fieldbus systems not only ensures electromagnetic interference-free communication between all devices but also guarantees high data integrity, immunity to vibration, and comprehensive diagnostic capabilities.
Taking a coal mine as an example, this factory has two transport stations, two coal mills, and a landfill for handling coal waste. Between these stations, coal is transported via several conveyor belts. A crucial task during the coal's transport through various stages is recording detailed data. Each conveyor belt has its own control cabinet, equipped with connectors, motor circuit switches, and distributed I/O. Modular I/O stations, using network protocols such as DeviceNet, transmit analog and digital signals to a higher-level PLC system. These signals reflect the status of the transport system, including feed rate, bias, and material level data. After evaluating the acquired data, the PLC submits the factory status to the information management system. All control is achieved through two Fieldbus control networks.
Because of the reliable, efficient, and flexible Fieldbus technology, which provides fault-tolerant products, manufacturers are confident in achieving continuous coal transportation. Utilizing an IP67-rated Fieldbus system, this solution meets the high requirements of coal production enterprises and features simple maintenance, rapid diagnostics, easy installation, low error rates, and low cable costs, ultimately ensuring efficient and safe plant operation even in harsh environments.
in conclusion
No two factories have the same manufacturing environment. However, manufacturers share a common goal: to maximize production efficiency, capacity, and profit margins while producing high-quality products. The integration of control equipment, such as PLCs, and advanced enterprise networks provides the strategic preparation for achieving these goals.
Current network technologies enable high-speed, secure, and reliable data transmission across the entire plant. PLCs , with enhanced diagnostic and communication capabilities, provide intelligent, low-maintenance systems that can bring significant benefits to the factory. Manufacturers can now improve accuracy, deliver faster production speeds, reduce errors, and save on material and labor costs.
