Tech Spotlight: The Difference Between Standard Ethernet and Industrial Ethernet

Introduction

The term “Ethernet” refers to networking technology used in home and office environments. Industrial Ethernet is Ethernet used in an industrial environment. The two terms, although they share a common word, are functionally different. Both Industrial Ethernet and Ethernet have their own characteristics and bring unique benefits. The purpose of this article is to explain the difference between standard Ethernet and Industrial Ethernet.

Ethernet and How it Works?

Ethernet is a kind of networking technology based on the “master-slave” principle.  A wired network is set up in a local area within a building. Devices present within that area, as part of an office, school, or even a home setting, get connected. The Ethernet functions as a physical layer and data links the layers present within the network. This physical layer specifies electrical signals, signaling speeds, media, connector types, and network topologies. It also defines the formation of data packets and their transmission so that other devices within the network can recognize, receive, and process them. Ethernet connected devices use protocols such as TCP/IP, HTTP for mutual communication.

Until recently, Ethernet devices could have only a few hundred meters of cable between them.  This made the technology impractical when it came to connecting geographically distributed locations. Modern developments, however, have increased these distances, allowing Ethernet networks to span tens of kilometers. The Ethernet variants use a twisted pair or a fiber optic cable as the physical medium over which the data is transmitted. Figure 1 shows a simple Ethernet network where different types of devices are linked via standard Ethernet.

Figure 1: Ethernet Network in an office environment

Ethernet generally uses three types of hardware: Ethernet cards, Ethernet cables, and Ethernet routers. The Ethernet card (also called adapter) is installed in each computer which connects to the network via Ethernet cable. The latter is used to transmit and receive data packets across the network and from the Internet. It is available in various types such as Category 5 (Cat5) and Category 6 (Cat6) cables.

Multiple wires present in each cable allow data transfer in both directions, both to a computer and from it. The router or switch is the final hardware component of the network. The router performs the function of directing all the intra-computer data over the network. This allows the subscribed computers to share it and also serves as an Internet link.

The Ethernet is less susceptible to problems originating from radio frequency interference, physical barriers, or bandwidth hogs. Since there is physical cabling, it is a challenge to illegally access network data or hijack bandwidth for unsanctioned devices outside the official subscriber list. Thus, excellent network security and control are achieved.

Ethernet technology has developed to a stage where it can provide network intelligence, and this continual progress has made it a viable solution for industrial applications. The technology offers the following four data rates:

• 10BASE-T Ethernet provides performance up to a maximum of 10 Mbps.

• Fast Ethernet delivers up to 100 Mbps speed.

• Gigabit Ethernet extends speed up to 1Gbps.

• 10 Gigabit can support intelligent Ethernet-based network services, interoperate with existing architectures, and provides the high data rate of 10Gbps.

The Open Systems Interconnection (OSI) reference model constitutes the heart of Ethernet networking.  It describes information transfer from a software application present in one computer to a software application in another computer via a network medium. The OSI reference model splits the tasks involved in data transfer between networked computers into seven layers:

• Physical Layer

• Data Link Layer

• Network Layer

• Transport Layer

• Session Layer

• Presentation layer

• Application Layer

Industrial Ethernet

Industrial Ethernet is the Ethernet developed for the industrial environment. The technology requires rugged connectors, cables, and real-time data exchange capability. Industrial Ethernet applies the Ethernet standards written for data communication to manufacturing control networks as shown in Figure 2.

A switched Ethernet architecture is often used for industrial networking environments. Switches allow multiple users to send information over a network at the same time without mutual interference and hence no speed reductions occur.

Industrial Ethernet uses specific protocols to exchange real-time information. A few of the popular industrial Ethernet protocols are PROFINET, EtherNet/IP, EtherCAT, SERCOS III, and POWERLINK.

Figure 2: Industrial Ethernet

Fully switched networks use twisted pair or fiber-optic cabling. The two use separate conductors to send and receive data. A collision-free environment is thus created where data can be sent and received at the same time. Switches function at the data link layer of the OSI model.  The use of a switch provides the following advantages:

• Determinism—It ensures that a packet is sent and received in a specific time. Determinism is an important design goal for industrial networks.

• Latency— It refers to the time taken to transit between the source and the target in the network. Switches are characterized by low latencies.

• Data loss under congestion— Intelligent switches offer quality-of-service (QoS) features which prioritize critical traffic.  Congestion linked data loss does not occur.

How Industrial Ethernet differs from Ethernet?

A few parameters emphasize the differences between standard Ethernet and industrial Ethernet. These include communication needs, operations, and environmental challenges. Let's discuss the differences in greater detail.

Communication

Industrial Ethernet has a few particular requirements based on two-way communications. To understand this, we can take an example of a bottle filling factory running on an Industrial Ethernet network. The operation works as it uses handshaking between the PLC and the sensor to ensure message delivery. The bottle gets filled by the PLC command. When the bottle is full, the PLC orders the stop command.  It follows that in an Industrial Ethernet nework, the handshake saves time and money.

In an Industrial Ethernet network, crash detection is incorporated. If two messages collide in the network, PLC resends the message until it receives an acknowledgment from the device. When it comes to Ethernet use in an office or at home, intermittent data loss is acceptable.  Even if the webpage gets lost in transmutation, the page can be simply refreshed.

Operations

Factory operations and processes are viable concerns. The cost of downtime is one such major area of concern. When a network crashes in an office setting, it is at best an inconvenience.  The same inference cannot be made in a production environment.  Downtime makes for a costly affair in any industry.

Security

In an office environment, the information traveling through the network can be vital and confidential in nature. The network must thus be protected against unauthorized use. Industries share identical concerns. A potent security risk in an industrial setting includes that of an employee accidentally breaking the system and consequently creating a Garbage In/Garbage Out scenario.  This could bring the device or network to a complete stop.

Environmental Conditions

Environmental conditions such as temperature, noise, vibration, and the presence of chemicals may significantly influence the network:

• Temperature: Temperature highs and lows may considerably affect network functions. For example, it is not unusual for a cable to become brittle and break when bent in a normal way in subzero temperatures.
• Chemicals: The Industrial Ethernet environment can be described as a harsh one. All measures must be enforced to protect cables and connectors from the negative physical effects of an industrial environment.
• Noise: Electric and magnetic noise generated by heavy motors and high voltage devices may distort data transfers on the network. This interference may impede the throughput of the network or corrupt messages altogether.
• Vibrations: A few processes in the industrial environment create a vibration which can degrade the cable jacket and may break terminal connectors or loosen/disconnect connectors.

Office Ethernet components are designed for primary level use. The Industrial Ethernet components, in contrast,  are used in multiple levels and in varied environmental challenges.  Using premium consumer switches hubs and cables made for the office and home Ethernet in industrial applications works fine for a temporary period but they soon break down as they are not manufactured for industrial use.

Network Topology

Standard Ethernet is almost always configured in a star topology whereas Industrial Ethernet has different topology options such as star, tree, line and ring topology to fit in various industrial applications.

Cables and Connectors

Industrial Ethernet technology differentiates between cables and connectors. The presence of a harsh environment means an industrial application needs heavy duty and sealed connectors. Cabling is also different in industrial Ethernet. Industry cables must have a better quality of jacketing compared to regular Ethernet cables. The jacket encasing the heavy-duty cables and the metal should be of superior quality to make them durable.

Glossary

• Category 5 (Cat5): an Ethernet network cable standard defined by the Electronic Industries Association and Telecommunications Industry Association. Cat 5  transmits at 100MHz frequencies, providing a rated line speed of up to 100Mbit/s and a max cable segment length of 100 meters.
• Category 6 (Cat6):  standardized twisted pair cable for Ethernet and other network physical layers that is backward compatible with the Category 5/5e and Category 3 cable standards. It has to meet more stringent specifications for crosstalk and system noise than Cat 5 and Cat 5e. The cable standard specifies performance of up to 250 MHz.
• Ethernet: a family of computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN), and wide area networks (WAN).
• EtherCAT: (Ethernet for Control Automation Technology) is an Ethernet-based fieldbus system, invented by Beckhoff Automation. The protocol is standardized in IEC 61158 and is suitable for both hard and soft real-time computing requirements in automation technology.
• EtherNet/IP: (Ethernet Industrial Protocol) is a network communication standard capable of handling large amounts of data at speeds of 10 Mbps or 100 Mbps, and at up to 1500 bytes per packet. The specification uses an open protocol at the application layer. It is especially popular for control applications.
• HTTP: HyperText Transfer Protocol is an application-layer protocol used primarily on the World Wide Web. HTTP uses a client-server model where the web browser is the client and communicates with the webserver that hosts the website.
• POWERLINK: Ethernet Powerlink is a real-time protocol for standard Ethernet. It is an open protocol managed by the Ethernet POWERLINK Standardization Group. It is an Industrial Ethernet solution devised to give users a single, consistent and integrated means for handling all communication tasks in modern automation. It is generally suitable for all conceivable applications in machine and plant engineering as well as for process industry applications.
• PROFINET: is an industry technical standard for data communication over Industrial Ethernet, designed for collecting data from, and controlling equipment in industrial systems, with a particular strength in delivering data under tight time constraints (on the order of 1ms or less). PROFINET is the standard for industrial networking in automation.
• Router: is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet: is the third generation of the Sercos interface, a globally standardized open digital interface for the communication between industrial controls, motion devices, input/output devices (I/O), and Standard Ethernet nodes.  It is based upon and conforms to the Ethernet standard (IEEE 802.3 & ISO/IEC 8802-3).