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Mitsubishi CC-Link Networks Simplified
Bryon Sol posted a blog entry in Products & Technology*** Quick Update 6/27/2022 *** This is a great quick overview from Mitsubishi ----------------------------------------------------------------------------------------------------------------------------- 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 • CC-Link IE TSN • And SLMP (Seamless Messaging Protocol) Before CC-Link IE TSN came around the overview looked like this: 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. 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 and 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 CC-Link IE Field Network Basic 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. 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
Introduction to IP Addresses and Networking
Bryon Sol posted a blog entry in Products & TechnologyMaybe you are new to Ethernet Networking or maybe you’ve been doing it for a while and you know how to get it to work but fumble most of the time before getting it right. Either way, this blog is intended to give a basic understanding of Ethernet networking. We won’t get into more advanced topics like VLANs and DMZ, and if you haven’t even heard those terms, that’s fine. This is meant as a beginners guide. So let’s get to it. Firstly, let’s talk about your address. No, I don’t mean your city and state or even your country. But instead your IP ADDRESS! IP is just the abbreviation for Internet Protocol. Your IP Address is where your PC lives on the network. It’s as simple as that. What’s more complicated is that there are different networks. For people new to networking, we think that everything these days is internet connected, but that’s just not true, and honestly we probably don’t want everything directly connected to the Internet, that would make things more vulnerable than they need to be. But for now let’s start with your company’s network and the internet so we can explain what happens on that type of network. Let’s pretend instead of your PC being a computer, let’s imagine that you are a student starting mid-semester at a new school. When you arrive at school on your first day, you wouldn’t just walk in and sit down at any desk. You are aware that people probably have assigned seats so you would ask the teacher where you could sit right? Well your PC does the same thing on a company network. When it arrives it asks for a “seat” from the teacher. In this case the seat is an IP address and the teacher is a device on the network called the DHCP Server. When you connect your PC to a network via WiFi or a company wired network, you are almost always using DHCP (Dynamic Host Control Protocol) to be provided an IP Address so that you don’t conflict with other computers on the network. Okay, great. So you have an address, you know where you are. But – do you know how to get a message to someone else? If they are in your classroom with you (to extend the metaphor), you don’t need any help getting them the message. You just talk to them directly. This is because they are part of your SUBNET. Because of what’s called the Subnet Mask, our PC can know who it can talk to without any help. We can communicate with all of the PCs and devices that are on our same Subnet. But if someone is outside of our subnet we need help passing the message along. The device which passes the message along is called the Gateway. A common IP address used on home networks and sometimes small networks will be something that looks like 192.168.0.X where X changes for each device. The typical subnet mask used along with this IP address is 255.255.255.0. To keep this simple, just understand that the 4 numbers of the IP address mate up with the 4 numbers in the subnet mask. So: - 192 mates with the first 255 - 168 mates with the second 255 - 0 mates with the third 255 - X mates with the 0 at the end And at the simplest level. If you see 255, this tells you that the numbers MUST match for communication to work without needing someone to help. So if both devices have a subnet of 255.255.255.0 then all 3 first numbers in their IP addresses must be the same or the two devices won’t talk to each other without someone helping. You can think of it kind of like this, an IP Address has four parts: Town.School.Classroom.Seat As far as Subnet mask is concerned, if the Subnet Mask says 255=the number must match, 0=doesn’t matter for communication. There’s a lot more to this, but we are trying to keep this simple. Therefore if we had subnet of 255.255.255.0 it indicates that Towns must match, Schools must match and Classroom must match. Then for example 192.168.0.100 can talk to 192.168.0.22. But 192.168.0.100 can’t talk to 192.168.1.22 because their third octet (classroom) doesn’t match. You can find a much more detailed description here of how this works if you’d like to read it. https://docs.microsoft.com/en-us/troubleshoot/windows-client/networking/tcpip-addressing-and-subnetting Great, so we are starting to understand the terms. IP address is our specific location, subnet mask is who we can talk to without help, and Gateway is the helper to talk to people outside our classroom. What about if we know someone’s name, but not their address? How do we talk to them? That’s where DNS servers come into play. Think of the DNS server like a phone book. If you know someone’s name you can look up their number. When you connect to a company network, typically the “Obtain an IP Address automatically” box is checked. Then the DHCP server will give you ALL of the information on this page. It will give you an IP Address, an appropriate subnet mask, the address of the Gateway and a couple of possible DNS servers to use, so when you want to get to http://www.gibsonengineering.com you can find out the address. And when you want to send information to Gibson Engineering, you will give that information to the Gateway device and it will pass it along for you. So overall things kind of look like this, where the Gateway is allowing the connection to the internet – in this picture imagine the cloud as the internet. Okay, so that takes care of the company network and getting internet access. But what about my industrial network? Well here’s the trick - we want to keep them separate! If my company network has 172.16.20.X addressing then we can use 192.168.0.X addressing. But if it uses 192.168.X.X already, then I want to pick something different. Why? Because we don’t want confusion. Remember my analogy of Town.School.Classroom.Seat? Well in the USA there are 88 towns named Washington. There are 399 instances of schools named Lincoln in the USA. Even if we have two separate network cards in the PC we are using, if the towns and schools are the same, how does the software I’m using know where to send the message? Having two network cards in a PC actually allows me to communicate on two separate networks simultaneously, but if they are both using the same addressing scheme then it still won’t work. However, subnetting will often allow things to be very close and not cause conflicts. For instance, my company network could be using 192.168.0.X addresses with a subnet of 255.255.255.0 but if I wanted to, I could set up all my PLCs and HMIs and barcode readers and cameras and other industrial devices on 192.168.1.X addresses and if my subnet for that card is 255.255.255.0 then there are no conflicts. This is why Mitsubishi choses to default to 192.168.3.X IP Addresses for their devices because they know that most likely this won’t interfere with most company networks by default. So in the end, I’m often setting up my computer to look something like this: To summarize, we usually have two separate networks in Industrial Automation. Our machine network and our company network. They must have two different numbering schemes to prevent conflicting addresses, and the IP addresses and subnet masks must match for things to be able to communicate. Quick checklist for troubleshooting connection problems: 1) Do you know the IP address of the device you want to talk to? i.e. 192.168.3.18 2) Is your IP address in the same range? i.e. 192.168.3.X anything other than 18 3) Do your subnet masks match? 4) Is your IP address unique? Is something trying to use the same address? If all of the above looks correct, it’s often a cabling problem or a conflict with some other software such as Firewalls or Antivirus software preventing the software from talking. As networks get more complicated and security becomes a bigger concern, there will always be things not covered by this article. But with a good general understanding of how networks work, you can usually solve most networking issues.