I am not an engineer. I have a great deal of respect for the profession and once considered pursuing the field in college. However, I after took two trigonometry classes (not courses, two class periods) I had determined two things: I was not cut out for a career that involved heavy coursework in math, and triangles are without a doubt the least interesting topic of study. I am sure that my professor must have been a blast at cocktail parties. Now here I am with my business degree, surrounded by engineers who were able to make it past trigonometry (some of whom I understand are triangle enthusiasts), about to tell you about EtherNet/IP. This blog post is not meant for the control engineer. Rather, this post is written for people who, like me, have no interest in learning complex math but have found themselves in a situation where learning about EtherNet/IP could benefit them.
Ok, So What is EtherNet/IP?
To understand this, you need to have a grasp on what Ethernet is as well as the Common Industrial Protocol (CIP). In simple terms, Ethernet is a method of connecting and networking groups of computers together to form a Local Area Network. CIP, on the other hand is a data representation, connection management and messaging protocol that has universal applications over many transport and physical layers. In simpler terms, it’s a way of saying that if you want these machines to be able to communicate, your data must look and behave this way.
Now that you’re an expert on CIP and Ethernet, or at least understand what they are, we can talk about EtherNet/IP. EtherNet/IP is the adaptation of Ethernet to fit the CIP standard. It’s become one of the most common ways for manufacturers throughout the world to connect industrial automation devices. EtherNet/IP is advanced in the sense that it offers greater bandwidth than other industrial protocols.
The Origins of EtherNet/IP
During the 1980s, it became more and more difficult for industrial networks to keep up with the increasing quantities of data that needed to be communicated between machines. Other industrial protocols like Modbus and DH+ were slowly becoming obsolete because of the rapidly increasing speeds of automation. Factories needed something with a little more bandwidth to keep up but were slow to adapt. Their colleagues in the corporate offices began to implement Ethernet to connect their office computers and peripherals. This led to the ODVA creating EtherNet/IP near the turn of the century.
What’s So Great About EtherNet/IP?
Today, EtherNet/IP is utilized for connecting any number of different devices on the factory floor and uses a scanner-adapter relationship. You can think of the scanner device as being the boss and the adapter as the subordinate. The scanner gives commands to the adapter in the form of input data and the adapter responds to the request via output data. For example, a Programmable Logic Controller (PLC) might send an input to a thermometer asking for the temperature of the machine. The thermometer, acting as the adapter, would respond with the output containing the temperature of the device.
What separates EtherNet/IP from other industrial automation protocols is that adapters can accept connections from more than one scanner. With other protocols, such as Modbus RTU, slave devices can only connect to one master device. A scanner device can connect to and access the data of any number of adapters. However, only one scanner can control the outputs of an adapter. Other scanners can monitor the output of an adapter.
By now, you should be cocktail party literate on the subject of EtherNet/IP. Although, I cannot imagine that there are very many cocktail parties where the theme is industrial protocols. If there are, I certainly haven’t been invited. On the bright side, if somebody approaches you at a cocktail party and tries to talk about trigonometry, you can quickly divert the subject to EtherNet/IP. This may come in handy later.
For a deeper look into EtherNet/IP, I recommend giving The Everyman’s Guide to EtherNet/IP a read. It’s a fantastic beginner’s guide to understanding this industrial protocol.