Abstract: CC-Link IETSN is the first industrial network to apply TSN technology. This article introduces the development process of industrial bus networks, as well as the technical characteristics and application areas of CC-Link IETSN network.
introduction
With the rise of the Industrial Internet of Things (IIoT) globally, future industrial systems will require rapid responses in formulation, design, and production to meet diverse customer needs, achieving truly flexible and customized production. This will also necessitate improved product quality, increased capacity, and reduced overall costs. To realize this "variable" production, an increasing amount of information will need to be collected and processed, including operational, order, material, production site, and logistics data. Therefore, the connection between IT (Information Technology) and OT (Operational Technology) needs to be closer. CC-Link IETSN, as one of the world's earliest industrial networks based on TSN (Time Sensitive Networking) technology, is in line with this trend.
Development of Industrial Networks
Throughout industrial development, starting with the electrical automation of Industry 2.0, industrial networks have played an irreplaceable role in the entire industrial system. In the early days of industrial bus networks, RS-232 serial communication was the first to capture the market. However, it encountered various problems during use: firstly, common-mode interference; secondly, its maximum capacitance of 2500pF severely limited its transmission distance and speed, with reliable communication distance in the field limited to only 15m and a communication speed of around 20Kbps. Furthermore, point-to-point communication was insufficient to meet the needs of industrial production lines.
To address the issues of distance and speed, RS-485-based serial communication was developed. It optimizes the transmission and reception method based on RS-232 and uses a two-wire system to achieve 1-to-N communication, increasing the communication speed to a maximum of 10Mbps and the total distance to over 1000m. Although the communication has changed from full-duplex to half-duplex, it better meets the real-time requirements of industrial scenarios. Currently, there are many RS-485-based industrial bus networks on the market, such as CC-Link, Profibus, Modbus, and CANopen bus protocols.
By the late 20th century, industry experienced another significant leap forward. Applications such as Messaging Systems (MS), ERP systems, and SCADA systems placed even greater demands on the volume and speed of data transmission on the production floor. Simultaneously, the rise of the internet greatly impacted industrial networks, leading to the development of industrial networks based on standard Ethernet, such as CC-Link IE, ProfiNet, Modbus/TCP, Ethercat, and Ethernet/IP. These networks, utilizing standard network cables, connectors, and flexible topologies, greatly facilitated on-site construction. Furthermore, communication distance and speed were further improved, extending the distance between devices to 100 meters and achieving speeds of 100 Mbps or even 1 Gbps.
In recent years, with the implementation of the Industrial Internet of Things (IIoT), more and more IT-based applications need to interact with OT (Operational Technology) information in the field, posing severe challenges to network speed and data volume. At the same time, the market has higher requirements for the use of ordinary Ethernet devices and the high precision of driving equipment. For these reasons, TSN (Transportation Signal Network) technology has officially entered the industrial network field. CC-Link IETSN, as one of the earliest industrial bus networks to apply TSN technology, provides faster network speeds, larger data capacity, and higher network utilization while meeting the convergence of IT and OT needs.
CC-LinkIETSN Technology Features
Integration of control information and production management information
CC-LinkIETSN prioritizes control information from field devices, allocating bandwidth over production management information. This enables real-time cyclic communication control of field devices, ensuring the timeliness of control information while also allowing direct information retrieval from terminal devices via TCP/IP protocol. The two protocols coexist on the same network cable without interfering with each other, saving on field wiring costs and truly realizing the integration of IT and OT.
Figure 1. TSN Technology and Protocol Layer
Quickness of system setup and repair
SNMP, as a universal simple network management protocol, is also compatible with CC-Link IETSN. Using ordinary Ethernet diagnostic tools with corresponding SNMP, you can not only easily monitor CC-Link IETSN compatible products, but also collect and analyze data from ordinary Ethernet switches, industrial cameras, vibration detectors and other devices, while also providing big data for artificial intelligence.
By adopting the clock synchronization protocol in the TSN specification (referencing IEEE 802.1AS and IEEE 1588V2), the time between various compatible products can be calibrated to maintain high-precision synchronization. Utilizing the clock synchronization function of CC-Link IETSN compatible products, the time point of failure can be quickly identified in the operation log, helping to identify the cause of the anomaly and quickly restore network normal operation. Simultaneously, it can provide the upper-level IT system with the field status and corresponding accurate time. By analyzing information such as power consumption and vibration, pre-maintenance or early replacement of field equipment can be performed, significantly reducing maintenance costs.
Increased production cycle time and maximum network utilization
CC-LinkIETSN achieves minimal link scan cycles, significantly reducing production time and increasing overall plant productivity in industrial settings. Furthermore, CC-LinkIETSN utilizes time-division multiplexing (IEEE 802.1Qbv) to define multiple link scan cycles within the same network. Corresponding link scan cycles can be set for the characteristics of different products; for example, high-speed cycles can be defined for servo systems and security devices, while medium- or low-speed cycles can be used for temperature and humidity sensors. This maximizes network bandwidth utilization and improves overall plant productivity.
Diversity of development methods
CC-Link IETSN compatible products can be developed not only through dedicated ASIC or FPGA hardware, but also through software protocol stacks on general Ethernet chips. The communication speed can also be selected according to the characteristics of the product, such as 100Mbps or 1Gbps, which greatly facilitates equipment manufacturers to choose the development method according to their own conditions.
CC-LinkIETSN Application Scenarios
CC-Link IETSN, employing TSN technology, fully utilizes standard Ethernet devices while redefining protocols to achieve high-speed control communication, meeting the needs of various industries. For example, in the automotive industry, general and safety communications can be mixed on the same network cable; in the semiconductor industry, large volumes of menu and traceability data can also be communicated at high speed, and mixed communication with HSMS will not affect the timing of control information; in the lithium battery industry, by combining high-speed control ( servos , etc.) and low-speed control ( inverters , temperature controllers, etc.) with communication cycles, device performance can be ensured and the optimal equipment can be selected according to the application.
Figure 2 CC-Link IETSN System Architecture Diagram
Conclusion
As a development direction for industrial network technology, TSN technology will lead to the emergence of more and more networks based on it in the future. CC-LinkIETSN will achieve interconnection and interoperability with these networks, promoting the development of the Industrial Internet of Things. (Originally published in the sixth issue of "China Instrumentation")
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