I write this in early April of 2020, and right now there isn’t any baseball. No basketball playoffs. No hockey championships. But there is the perennial contest “my protocol is better than your protocol.” This week’s contestants are EtherNet/IP and CC-Link (Control and Communication Link).
CC-Link appeared on my radar again this week as there is a renewed effort going into reintroducing it into the United States. CC-Link is the ever-popular communications protocol of Japan and Mitsubishi. In fact, it owns a stunning 90% of the Japanese market. So, the infrastructure of products, tools, knowledge, and everything else exists to make it popular in the US – now it needs to get traction.
This has been an ongoing effort for a long, long time. The CLPA (CC-Link Partner Association) has tried for years to promote CC-Link. I’ve seen their tradeshow booth at big and small events over the years, but the membership has never grown beyond a handful of companies that do business in Japan. Last year (2019), the organization was shaken to its roots with most of the staff fired and new leadership brought in to make it successful in the US.
So what is CC-Link and what are its advantages over EtherNet/IP, PROFINET IO, and other protocols that are more heavily used in the US? Why would anyone give it more than a passing glance? Let’s take a look at it in more detail.
What is CC-Link? CC-Link is a high-speed, high-performance industrial network technology that enables devices from numerous manufacturers to interoperate, resulting in a fast, highly deterministic control system. Right off the bat, we see a clear advantage to CC-Link: determinism. CC-Link promises that you can deterministically know exactly when a message is going to arrive.
EtherNet/IP and others can’t really offer that. They rely on the fact that most process and discrete control systems in the US don’t need much in the way of determinism. They achieve a pseudo-determinism by organizing their network architecture to use switches to segment traffic and limit the broadcast domain. That’s good enough for the majority of industrial applications. The remaining applications are typically motion applications, and they use special motion control technologies like EtherCAT, Sercos, or PROFINET IRT.
CC-Link isn’t just one network. There are actually four fully compatible open technology CC-Link networks. These technologies can be used together in an integrated solution, or separately as needed. There is CC-Link/LT (somewhat similar to IO-Link), CC-Link Safety, CC-Link (original version), and CC-Link IE (Ethernet-based).
CC-Link IE Field is a 1-Gigabit Ethernet-based integrated network designed to meet the changing demands of optimized control, openness, reliability, and deterministic handling of data in industrial applications. It is supported and promoted by the CC-Link Partner Association (CLPA). CC-Link IE enables seamless data communication from the plant-level enterprise network to the production floor network. This integrated industrial network philosophy also provides cost reduction for the total system engineering task from system start-up through operation and maintenance. The biggest differentiation between CC-Link IE Field and other Ethernet-based protocols are its high speed and determinism.
The CC-Link IE Field network is the one that is most equivalent to the industrial networking technologies we use in the US. Some of its key features include:
- Information processing for maintenance and diagnostics
- High-speed 1Gbps data transmission using standard Cat5e copper cable and RJ-45 connectors
- Determinism through a token-passing technique that does not require additional switches
- Seamless communication from the enterprise to the controller network layer to the field network layer
Is CC-Link destined to gain a wide share of the US market? Even though it offers some benefits not found in US technologies, it is unlikely to gain much market share as it currently doesn’t interoperate well with Siemens and Rockwell Automation programmable controllers.