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Mitsubishi CC-Link Networks Simplified

Bryon Sol

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Mitsubishi CC-Link networks have grown substantially over the past decade and it’s no wonder that there is some confusion on the various versions.  This blog is to give a quick overview and hopefully clear up some of what can be rather muddy waters.

Let’s start with what CC-Link is:  CC-Link is a FAMILY of protocols created and maintained by the CC-Link Partner Association (https://www.cc-link.org/)

Very much like other industrial communication protocols, it is used to communicate between industrial devices.  CC-Link is also an open standard meaning that it is not controlled by Mitsubishi, but instead the CC-Link Partner Association and many vendors participate in this Association to promote a standard that works throughout the world.  There are over 250 companies participating as members of the CCLPA in all sectors of Automation and Industry.

The number of products which communicate using one of the various versions of CC-Link is increasing steadily.  In 2005 there were 740 products on the market and in 2019 there were almost 2100, so a 3 fold expansion and the product offerings continue to expand.

So why is there confusion in the market over CC-Link products?  I believe a lot of it comes down to nomenclature.  Just like Modbus had Modbus RTU, Modbus ASCII, and Modbus TCP, CC-Link comes in many versions:

•    CC-Link
•    CC-Link/LT
•    CC-Link Safety
•    CC-Link IE Field Network Basic
•    CC-Link IE Field
•    CC-Link IE Control
•    CC-Link IE Safety
•    And SLMP (Seamless Messaging Protocol)
506271453_AllTheProtocols.png.d08bc727616f8323a01665555d279f70.png

Before CC-Link IE TSN came around the overview looked like this:

347860601_Pre-TSNNetworkOverview.png.a0d7d2198103df21156df5508e72b0a0.png

It’s also important to understand what is involved in the various protocols in regards to hardware and software which can be explained with this graphic, again this is prior to TSN.

281654998_NetworksandHardwarevsSoftware.png.8e17fdd255267e2bde949e50df0c9288.png

It can be somewhat easier to understand if we look at this from a historic perspective.  Starting with SLMP.  SLMP is simply the messaging protocol used.  It is the data packet structure that goes back and forth between the devices.  Then we use RS-485 hardware as the underlying transport for classic CC-Link.  Stepping up in time the CLPA created CC-Link IE Field and CC-Link IE Control.  CC-Link IE Control is Ethernet based on a Fiber Optic network for high speed token based data transfer and it is usually used for machine-to-machine communication when a lot of data needs to be sent and full determinism is critical.  CC-Link IE Field on the other hand is based on standard copper Ethernet and can use ring, line or star networks.  Both CC-Link IE Control and CC-Link IE Field need to exist as their own stand-alone network.  If you look at the model above you can see that they exist right on top of the Ethernet hardware, they are very low-level protocols and do not rely on the IP Stack and TCP/UDP protocols.  Because of this, these networks (CC-Link IE Field and CC-Link IE Control) must be kept on their own hardware separate from classic business networks.  This is where CC-Link IE Field Network Basic comes into play.  CC-Link IE Field Network Basic is a fast, Ethernet based protocol that rests on top of the TCP/UDP stack.  This means that it can coexist with other standard Ethernet traffic and you can connect it to standard business class Ethernet switches along with your normal network traffic.  The downside of this, is that CC-Link IE Field Network Basic is non-deterministic and the time from packet to packet can change depending on network traffic.

This finally brings us to CC-Link IE TSN.  TSN stands for Time Sensitive Network.  Without getting too deep into the technology, the TSN network allows high speed deterministic networking that has the potential to be even faster than CC-Link IE Field or CC-Link IE Control.  It also will be capable of existing on networks with other traffic, as long as the switching hardware that is used is designed to accommodate it.
 

pic_cclinkie_tsn_01.png.77faed55cebf3a9470dcef932bb2347a.png

As a general rule of thumb, here are the details and uses of each network (and like all rules-of-thumb, there are exceptions!).

CC-Link (including CC-Link, CC-Link/LT and CC-Link Safety)
-    Serial based network for device level control
-    Works for small networks of devices with speeds up to 10Mbps
-    Great low cost option for sensor networks, VFDs, and actuators like IAI Robocylinders
-    not intended for coordinated motion control or large volumes of data

CC-Link IE Field Basic
-    Ethernet based network for machine level communication using CAT 5E or CAT 6 cabling
-    can co-exist on standard business type networks using standard business class switches and hardware
-    intended for device level control such as sensors, valve banks, VFDs, etc
-    cannot perform coordinated motion control, and is non-deterministic

CC-Link IE Field
-    Ethernet based network for machine level communication using CAT 5E or CAT 6 cabling
-    cannot co-exist on standard business type networks, it must be separated to a network only running CC-Link IE Field devices, uses a token based network
-    intended for high-speed, deterministic communication and is often used for servo motion, industrial Robot communication, and deterministic remote I/O

CC-Link IE Control
-    Ethernet based network for inter-machine level communication using fiber optic cabling
-    Intended for larger volumes of data and a high speed network for synchronizing data between large systems such as different manufacturing cells on the same manufacturing floor

CC-Link IE TSN
-    The newest network, this network works on standard copper Ethernet and should use CAT 6 cabling
-    provides real-time communication between devices on a deterministic network
-    uses a time sharing technology as opposed to a token based system
-    allows for even higher-speed coordinated motion control than CC-Link IE Field
-    can co-exist with standard business level traffic on the same network if properly enabled Ethernet switches are used
-    devices such as VFDs, servo motors, and high speed inspection cameras can all co-exist on the same network and achieve communication speeds previously not attainable

As the main take-away, I hope you have been able to pick up the main differences between these various networks.  Each is it’s own unique system and for the most part there are no converters or ways for the different networks to communicate with each other unless it’s done through a PLC or other specialized hardware.  So choosing the correct hardware in terms of a control platform and devices can be somewhat confusing, but hopefully you now understand the differences.  And if you need any help in choosing a network or components, please reach out to Gibson Engineering as we are here to support you in navigating these various technologies.

For more reading:
CC-Link IE and CC-Link IE TSN details here:
https://www.mitsubishielectric.com/fa/products/cnt/plcnet/pmerit/concept/index.html
 



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