Accelerate Smart Factory Construction With TSN Technology

Accelerate Smart Factory Construction With TSN Technology
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The CC-Link Partner Association has created a new industrial open network specification “CC-Link IE TSN” as the next generation CC-Link IE network. Article by CC-Link Partner Association.

The CC-Link IE TSN specification combines gigabit Ethernet bandwidth with time sensitive networking (TSN). TSN is an addition to the IEEE Ethernet related standards and is starting to become popular for industrial networks. TSN’s key benefit is that it allows the combining of real-time control communication with non-real time information communication while maintaining deterministic performance. This is not possible with conventional Ethernet.

CC-Link IE TSN adds TSN to increase openness while further strengthening performance and functionality. It also supports more development methods, enabling easier implementation on a wider range of equipment and increasing the number of compatible products and is expected to accelerate the construction of smart factories using the IIoT.

Development Background

As customer needs grow more diverse and advanced, there is a growing trend in manufacturing industry toward automation, reducing TCO (Total Cost of Ownership) and improving quality, together with embracing new manufacturing methods such as mass customisation. The information-driven society fuelled by IT-based data continues to develop, with the development of sensing technology, higher-speed networks, the spread of cloud/edge computing, and the development of AI (artificial intelligence).

We are also seeing the appearance of global mega-trends moving toward the use of the IIoT in manufacturing industry, such as Industry 4.0 in Europe, the IIC (Industrial Internet Consortium) in the US, Intelligent Manufacturing in China, and Connected Industries in Japan. All of these share a common goal: the creation of “smart factories” in which everything is connected, data is used to the fullest, and optimised manufacturing takes place autonomously.

In order to create smart factories, essential issues include gathering real-time information from production processes, processing it via edge computing, and then transmitting it seamlessly to IT systems. Toward that end, one crucial need when making the most of production site data is a network capable of high-speed, stable control communication as well as large-volume information transmission to IT systems. In other words, it is important to combine industrial networks at production sites with IT system networks.

A wide variety of industrial networks are currently in use. However, it is difficult to achieve interoperability between them, leading to “islands” of automation that decrease process transparency. Demand for TSN support will therefore increase, as this technology makes it possible to mix different networks on the same trunk line and provide real-time communication through time synchronisation.

CC-Link IE TSN was developed to meet this demand. In order to realise smart factories, productivity improvement through higher equipment performance and functionality is essential, along with advanced motion control. This is especially true in advanced industries such as semiconductor and battery manufacturing. CC-Link IE TSN builds on the benefits of CC-Link IE by improving communication functions and synchronisation accuracy. Thus the motion control capabilities have been significantly enhanced. CC-Link IE TSN has thus been created as a next generation industrial open network to accelerate the construction of smart factories.

Technical Overview And Utilisation Of Open Technology

CC-Link IE TSN’s protocol uses layers 3 to 7 of the OSI reference model, building on the TSN technology located in layer 2.

TSN consists of multiple international standards. The major standards are IEEE802.1AS (which defines the time synchronisation method) and IEEE802.1Qbv (which defines the time sharing method). Combining these to the Ethernet standard enables punctuality, ensuring transmission within a given period of time, and mixed implementation with other communication protocols.

CC-Link IE TSN uses the time sharing method, a revolutionary cyclic communication concept. Conventional CC-Link IE uses a token passing method. A station transfers transmission rights to the next station after transmitting its own data by transfer of the token.

In contrast, CC-Link IE TSN uses common time synchronised across the network. The input and output communication frames are simultaneously transmitted in both directions in a fixed time. Combining this method with TSN technology shortens the network cyclic data update time.

CC-Link IE TSN network devices can be examined using SNMP (Simple Network Management Protocol), which is widely used for monitoring IT networks. CC-Link IE TSN component information and statistical information are defined as extended MIBs (Management Information Bases), allowing general purpose SNMP tools to be used for network diagnostics.

CC-Link IE TSN offers four major features:

Integration of control communication and information communication. By giving a high priority to cyclic communication for device control and by allocating bandwidth preferentially over information communication, CC-Link IE TSN offers a network environment that communicates information with IT systems while controlling system devices with real-time cyclic communication. This mixture with information communication means that devices using UDP or TCP communication (such as machine vision systems) can be connected to the network for high accuracy monitoring, diagnostics and analysis.

Rapid system setup and advanced predictive maintenance. CC-Link IE TSN is also compatible with SNMP, enabling easier diagnosis of network devices. Until now, special tools were required when collecting device status information. However, general purpose SNMP monitoring tools can now be used to gather and analyse data from devices compatible with either CC-Link IE TSN or IP communication (such as switches and routers). This allows quicker system start-up times, and can reduce the amount of time and effort spent on system administration and checking the operating status of devices during maintenance.

The time synchronisation protocol regulated by TSN is used to calibrate time differences between devices compatible with CC-Link IE TSN, keeping them synchronised with high accuracy. Time information stored in both master and slave devices is kept synchronised to the microsecond. If a network error occurs, this makes it possible to check operation logs and accurately trace events up to the error in chronological order.

Maximise the performance of motion control and reduce cycle time. CC-Link IE TSN uses the time sharing method with time trigger and bidirectional simultaneous communication to achieve a cycle time of 31.25 microseconds or less. Adding sensors or increasing the number of servo amplifier axes required for control to expand a production line has minimal effect on overall cycle time in systems operated with CC-Link IE TSN. Cycle time may even be reduced compared with systems operated with conventional networks. This is achieved in the following way.

CC-Link IE TSN allows equipment with different communication cycles to be used together according to the performance of each device. Until now, devices connected to the same master station had to be operated using the same cyclic communication cycle (link scan time) throughout the entire network. CCLink IE TSN allows for multiple communication cycles to be used within the same network.

More options for device vendors. In order for conventional CC-Link IE to make effective use of its 1Gbps bandwidth, device development vendors had to implement both master and slave device functions with hardware, using dedicated ASICs or FPGAs.

CC-Link IE TSN supports implementation on both hardware and software platforms. ASIC and FPGA based hardware methods are supported. Moreover, development with software protocol stacks on a general purpose Ethernet chip is also possible for both master and slave devices. In all cases, 100Mbit and 1Gbit physical layers are supported.

Device development vendors, given these options for implementation (hardware or software) and communication speed (100 Mbps or 1 Gbps), can now use the ideal development method for devices compatible with CC-Link IE TSN. This will also benefit users by rapidly expanding the range of compatible devices.





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