PROFINET vs Ethernet: Definitions and a Comparison

What is the difference between PROFINET and Ethernet? Can you give us a PROFINET vs Ethernet comparison? We get these questions quite often. And they are kind of difficult to answer because PROFINET and Ethernet are complementing technologies, not competing technologies. This short post will illustrate the comparison between PROFINET and Ethernet.

ISO/OSI Model

Let’s start by looking at the ISO/OSI model, a seven-layer model that generically describes the abstraction layers of a communication system. Any network communication can be divided into a number of layers.

Ethernet Definition

IEEE 802.3 specifies the standards that makeup Ethernet. Ethernet sits on Layer 1 (physical layer) and Layer 2 (data link layer) of the ISO/OSI model. Ethernet defines two units of transmission: packet and frame. The frame includes information such as the MAC addresses of sender and receiver, virtual LAN (VLAN) tagging, and Quality of Service (QoS).

Nowadays, Ethernet is the most common communication medium worldwide. Ethernet is used to connect nodes in a Local Area Network. The physical link between nodes in an Ethernet network can be for example a coaxial cable, a twisted pair cable, or a fiber optics cable.

PROFINET Definition

PROFINET is an Industrial Ethernet solution. It is a communication protocol to exchange data between controllers and devices. Controllers can be PLCs, DCSs, or PACs. Devices can be I/O blocks, vision systems, RFID readers, drives, process instruments, proxies, or even other controllers.

PROFINET sits on Layer 7 of the ISO/OSI model since it is an application. It defines cyclic and acyclic communication between components, including diagnostics, functional safety, alarms, and other related information. Also, PROFINET is based on standard Ethernet for its communication medium. High bandwidth, large message size, and versatility are just some of the benefits of having Ethernet on the factory floor.

PROFINET vs Ethernet

If you encounter a PROFINET network, you will notice the Ethernet cables connecting PROFINET components. If you then continue to configure the network, you will work with PROFINET controllers and devices. PROFINET allows you to build a network configuration and define the data exchange between controllers and devices in an automation network.

All in all, it is difficult to make a comparison between PROFINET and Ethernet because they are different in nature. Ethernet (Layer 1 and 2) defines the electrical signals within the wire, how to access the bus, and how to send and receive telegrams in a LAN. PROFINET is an application (Layer 7) based on Standard Ethernet for Layers 1 and 2.

-Nelly Ayllon