Interoperability is the ability of a machine or product to exchange or send information and the ability for a node receiving the data to process and utilize the information. The key to success is open platforms where nothing is proprietary and for those platforms to work with other products, present, past and future to operate with no restrictions. Quite utopian.
Ethernet IP defined
When trying to connect devices, we often run into the protocol of Ethernet IP in the United States. Let’s take a minute to further understand that protocol. To start, Ethernet IP can be confusing because of the terminology used in the industry. Ethernet works off the standard TCP (transmission control protocol) and IP (internet protocol). When you combine the two terms the IP in Ethernet IP stands for industrial protocol. Are you crossed eyed yet? We were. This can be confusing but is important for understanding the system.
Ethernet IP uses media, jacks, and connections. Ethernet IP is included in CIP (Common Industrial Protocol) which is the governing body that manages protocols. If the ODVA standard is met, the protocols can communicate accordingly. ODVA allows different manufacturers to speak to each other within protocols. This is important to remember when specifying devices for implementation. Furthermore, Ethernet IP is an object-oriented protocol. When looking at data each package has information on where are we going, what speed may be needed, what is coming back. These are all objects within a device profile.
So why should we care about device profiles? Let’s use an example where you want to send information from a device across your network to use that data somewhere else in your process. How would you do that? Ethernet IP allows for two potential paths to execute this. They are explicit (class 2 – event-driven) & implicit messaging (connected IO). Why does this matter? Bandwidth is key and everyone is fighting for it. For instance, if you wanted to monitor faults in a variable frequency drive (VFD) you would utilize explicit messaging because you only want to trigger information when an issue occurs. On the other hand, if you need to monitor or view parameters on a continual basis you would set up the device profile with implicit messaging which essentially is the same as connected IO.
When things go wrong with Ethernet IP and how to get around it.
Issues can arise when components trying to be utilized are not ODVA certified. You should also look at the objects you are trying to utilize and ensure you are following the correct structure to ensure items are interoperable. Because of ODVA, the main object functions should be the same between manufacturers; however, they do have leeway with other objects, and this is often an area where errors occur, and interoperability can become a hurdle.
Protocol converters are utilized from going from one protocol to another. The amount of data and speed should be considered when looking at converters. Buffering can cause issues and applications are really the determining factors when trying to use this in your process. They can work and do a great job but make sure you look at all the components associated with the data you are moving to ensure you get the desired system speed for the process.
Protocol selection is key!
Try to standardize on a protocol that is widely utilized in industry. Industrial ethernet-based protocols are highly recommended. Market share for industrial ethernet protocols is growing and the trend shows that this will be a predominant leader for the industry in the future.
