CC-Link IE is based on the Ethernet standard IEEE 802.3, and allows for ring, line and star topologies. In addition, the line and star topologies can be combined together to provide systems that offer the maximum application flexibility. The ring and line connections are particularly attractive, as they permit simple “daisy chaining” of devices, meaning the added cost and complexity of network switches can be avoided.
Addressing cybersecurity concerns
One of the key concerns related to the increasing adoption of industrial Ethernet is cybersecurity. While the use of internet-based technologies has increased the possibilities of what can be achieved in manufacturing, it has also increased the threats.
Some industrial Ethernet protocols are based on a standard TCP/IP (UDP/IP) stack, which can arguably cause some security vulnerabilities. CC-Link IE combines the physical and data-link layers of the OSI hierarchy with an open protocol that extends from the network to application layers. The result is an open, but controlled knowledge base that CLPA partners are free to implement, but reduces the exposure to unauthorized use.
Another concern potential users may have regarding the protocol is its compatibility with TCP/IP (UDP/IP) traffic. While current network-design practice encourages segmentation of networks for security and performance reasons, sometimes it’s still necessary to support non-control related network traffic. CC-Link IE supports this with the capability to encapsulate TCP/IP (UDP/IP) packets for transmission across the network, thus allowing this traffic to “tunnel” through the CC-Link IE system.
CC-Link IE also allows considerable application flexibility by supporting multiple protocol types on the same network. This reduces costs and increases maintainability. In addition to the standard I/O control, it also offers safety (SIL3), motion control and energy management on the same cable. This allows the CLPA to offer a cost-effective, simplified, flat network architecture that meets the needs of nearly all applications in the discrete sector, according to CC-Link.
Speed and simplicity
CC-Link IE’s basic communication technique is based on a shared memory model. All the devices on the network occupy an area of the controller’s memory. To communicate with them, it’s only necessary to change the value of the data in the area corresponding to the relevant device. The network automatically handles the traffic via the standard “cyclic” (synchronous) communication.
The same process happens in reverse for communication to the controller from devices. For high priority, unscheduled events such as alarms, or lower priority non-cyclic transmissions such as diagnostic information, an alternative “transient” (asynchronous) communication method is available. The technology has been designed such that even high levels of transient traffic do not impact the deterministic regular cyclic communication, meaning normal system functions are not impaired and the scan cycle is completely deterministic.
Deterministic performance is achieved with a token passing method, allowing dependable system operation. In practice, this allows network update times to occur in a few tens of microseconds, depending on system size and configuration. CC-Link IE also offers the ability for redundant controllers, so even a controller failure will not necessarily result in lost production.
