An integrated network for the IIoT era

21 August 2017

Haruyuki Otani discusses the current IT system trends in manufacturing industry and explains how CC-Link IE can help alleviate issues at the field level.

Manufacturing IT system and batch management through the cloud.
Manufacturing IT system and batch management through the cloud.

The implementation of smart factory technologies such as Industry 4.0 is attracting much attention today and this requires integration and optimisation of the IT systems used at the management, production, and field levels. 

However, integrating the field networks with higher levels using IT can pose problems relating to the speed and capacity of the network and seamless connectivity. The CC-Link Protocol Family is an integrated factory automation (FA) network designed to resolve these issues.

IT systems in manufacturing industries consist broadly of three levels – manufacturing, production, and field. Traditionally, the management level has been located at headquarters, and the production and field levels at plants. In keeping with the trend of manufacturing globalisation many production and field levels are now dispersed across the globe which has resulted in the construction of systems appropriate to each region. Additionally, to achieve localised optimisation of management and IT systems, the management level itself is also often located regionally.

Global integration of manufacturing IT systems using the cloud carries with it many factors that need to be mitigated, such as fluctuations in exchange rates. This means that management information must now be available instantly in order to respond to these challenges. Traditionally, a custom-made IT system would be optimised for business operations, but this required enormous investment and time to arrive at a customised system, and came with the problem that the system might have become obsolete by the time it was in operation. Abandoning these custom-made systems and making use of cloud services to fulfill 80% of requirements allows business operations to be matched to services instead, improving management efficiency and agility.

System integration via the cloud makes networking at the production level easy and secure with vertical integration of management systems. OPC-UA is increasingly also coming into play here, offering greater ease of vertical integration. It also provides a security function.

The field networks need to be addressed in terms of the ease of their integration with production, given the constraint of real-time operation. The attitude toward security also differs at the field level as consistent productivity is required even in the case of an incident. Safety at this level is also vital. Because the field level will often comprise a variety of networks, seamless connection is required to straddle different layers of networks.

Future manufacturing IT systems
In the future, cloud applications will be adopted to support big data and artificial intelligence (AI), while the manufacturing industry will increasingly make use of applications such as preventative maintenance to minimise facility downtime; quality stabilisation to prevent variation in quality; and optimisation of production operations co-ordinated with the supply chain. To provide for these new applications, field level networks will need to be high-speed and large capacity to handle the ever larger quantities of sensor data.

Further, the trend away from mass production to mass customisation is now advancing into job production of multiple models. To achieve low-cost job production, technical issues must first be overcome. For example, depending on the product to be manufactured, the field networks will need to be reconfigured for optimisation.

To sum up, the issues facing the field level networks include:

• Ease of integration with the production level under real-time constraints. 
•Guaranteed continuous production and safety. 
• Integration and seamless connection with different network types, including sensor networks. 
• High-speed / large capacity characteristics allowing new applications. 
• Ease of network configuration.

The open CC-Link family
The CC-Link Protocol family is composed of the CC-Link fieldbus based on RS-485, and the CC-Link IE industrial Ethernet uniquely based on 1 Gbps Ethernet. These provide a comprehensive open network architecture that focuses on performance and reliability while minimising cost. 

CC-Link IE is comprised of CC-Link IE Control, CC-Link IE Field, CC-Link IE Field Motion, and CC-Link IE Field Safety. CC-Link IE offers high-speed and large capacity. Sufficient bandwidth has also been provided for the addition of new applications in the future. CC-Link IE Field Basic has also been recently introduced in order to extend compatibility to 100Mbit Ethernet devices.

CC-Link IE Control has been widely adopted in the flat panel LCD and automotive manufacturing sectors because of its high-speed and real-time performance capabilities. In many plants recipe and quality control are important management items at the production level. CC-Link IE Control takes into account coordination and integration with the production level, such as recipe distribution and quality data retrieval.

In addition to cyclic communication CC-Link IE also offers real-time performance. Transient communication is also provided for recipe distribution, quality data retrieval, and so on. Additionally, the wide 1 Gb/sec bandwidth can be divided for cyclic and transient communication use, enabling the prevention of any disturbance to the cyclic communication period due to transient communication. PC card products for use in IPCs also exist, and quality analysis solutions can be constructed to apply the analytics tools on IPCs to the quality data retrieved via the card.

Ensuring safe, continuous production 
Security is provided by OPC-UA at the production level, and field networks are cost-optimised with a focus on design for productivity such as processing time. 

One of the most important requirements for the Industrial Internet of Things (IIoT) is to ensure that the data and information exchange between devices and services is secure and the OPC Foundation has worked with many security validation companies and organisations to provide the highest level of security. Because of the importance of OPC UA to Industry 4.0, the German Office for Information Security (BSI) performed an in-depth security analysis of the OPC UA specifications which confirmed that it was designed with a focus on security and contains no systematic security vulnerabilities.

Stefan Hoppe, OPC Foundation global VP, said: “In a connected world connectivity and interoperability have no value without security. The significance of BSI performing an in-depth security analysis and recommending OPC UA as the only known communication platform to address the complex security needs of Industry 4.0 cannot be underestimated.”

CC-Link IE Field Safety has been defined to realise safety communication using CC-Link IE. Safe communication can include communication between safety field devices and a safety controller as well as transmission and reception of safety data between safety controllers. When a single process is stopped by a safety function, other related processes are synchronised to stop, to allow for rapid restart following recovery.

For the CC-Link Protocol Family, SLMP (Seamless Message Protocol) has been defined as a mechanism for integrating and seamlessly connecting different types of field networks. This protocol enables connection from a higher-level system to field devices without considering the differences between CC-Link IE, CC-Link, and TCP/IP. In recent years there has been an increase in the use of open sensor networks, such as IO-Link, in networks at the field level, and the CC-Link Partner Association has also undertaken specification development for seamless connection with other open networks such as PROFINET.

CC-Link IE adopts Ethernet as the lower-level communication layer and token passing method as its higher-level communication control method. In the token passing method, data transmission rights – tokens – are relayed around the network between stations following a designated route. Only those stations having data transmission rights can transmit data. Currently, tokens are circulated around a statically determined route, but technically, it is also possible to change this route dynamically at random intervals. In the future, this will enable route switching depending on the product to be manufactured.

Simultaneous troubleshooting is also important in network configuration. It must be possible to easily find the location of trouble on the network. Various tools are provided for this purpose. For example, a management tool for network event history and a network diagnostic tool.

Solution strategies to address manufacturing IT systems and field network issues using CC-Link IE can be summarised as:

• Simple integration with the production level through use of transient communication which does not affect real-time performance. 
•  Reduced operation restart time following a safety stop through safety communication which coordinates between processes. 
• Consideration of seamless connection with other open networks. 
• With CC-Link IE, provision for high-speed/large capacity has already been ensured for the future. 
• Logical topology provided with no dependence on physical topology, using token passing method. 
•Straightforward troubleshooting. 

Haruyuki Otani led the technical task force at the CC-Link Partner Association.

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