What Is Profinet: A Comprehensive Guide

Profinet (Process Field Net) is a widely used technology in the field of industrial Ethernet. It provides a an open protocol for networking devices in industrial settings, allowing for efficient communication and control. In this article, we will explore the various aspects of Profinet and its significance in the industrial Ethernet landscape.

Understanding Profinet: An Overview

Profinet is a protocol that enables real-time communication between industrial devices such as programmable logic controllers (PLCs), human-machine interfaces (HMIs), and sensors. It offers a high-speed and reliable connection, making it ideal for industrial automation applications.

Profinet is based on Ethernet technology, making use of standard Ethernet infrastructure for communication. However, it extends the capabilities of traditional Ethernet to meet the stringent demands of industrial environments. Maintained by the Profibus and Profinet international organization, it has reliable message delivery capabilities, and is compatible with other Ethernet-based protocols such as OPC-UA and MQTT.

A Brief History of Profinet

Profinet was first conceived in 2000 at a meeting of the Profibus user organization. The first version was released in 2001, called Profinet CBA (Component Based Automation) - though despite being part of the IEC international standard in 2002, it was deprecated in 2014 due to a lack of adoption.

The next iteration of Profinet (called Profinet Input Output) was released in 2003 and received much better adoption. It was augmented with Time-Sensitive Networking (TSN) in 2019 - an extension of Ethernet standards designed to allow the transfer of data in time-critical environments where delivery needs to be guaranteed in defined situations. 

How Profinet Works

At its core, Profinet uses a variety of communication standards to form its network protocol within the OSI-model (Open Systems Interconnection), allowing for seamless integration into existing Ethernet networks. It supports both wired and wireless connections, providing flexibility in deployment.

Profinet uses a cascading real-time concept. The concept of cascading real-time refers to the ability of devices or network components to pass real-time data through a series of interconnected nodes or devices while maintaining strict timing requirements. This is critical for industrial automation use cases where time constraints are required.

A Profinet system consists of three types of devices:

• IO-Controller: this manages the automation task, which means controlling & monitoring one or more IO-Devices.

• IO-Devices: these are field-connected devices. It can consist of multiple modules and sub-modules.

• IO-Supervisor: this is often a software system installed on a host computer, and used to manage the settings of the system, and setting up the parameters & diagnosing individual IO-Devices.

A Profinet-IO system at the minimum consists of at least one IO-Controller that controls one or more IO-Devices. One or more IO-Supervisors can optionally be switched on temporarily for the engineering of the IO-Devices if required. Any automation device with an Ethernet interface can fulfil the functionality of an IO-Controller and an IO-Device at the same time.

The relationship between an IO-Controller and an IO-Device is defined by Application Relations (ARs) which in turn defines the Communication Relations (CRs) between IO-Controllers and IO-Devices.

The key strength of Profinet is its ability to foster rapid and reliable exchange of data, which is why it is primarily used in industrial automation use cases. It blends together different communication standards such as TCP/IP, UDP/IP, Profinet Real-Time (RT), Profinet Isochronous Real-Time (IRT), and Time Sensitive Networking (TSN).

For non-time critical applications, usually Profinet will use TCP/IP or UDP/IP. For time-critical applications, Profinet will use the other protocols (Profinet Real-Time, Profinet Isochronous Real-Time, and Time Sensitive Networking) to allow for precise & coordinated delivery of data between devices & nodes.

Key Features of Profinet

Profinet offers a range of features that make it a powerful solution for industrial Ethernet:

1. Fast Data Exchange: Profinet enables high-speed communication, allowing for real-time control and monitoring of industrial processes. With its low latency and high bandwidth capabilities, Profinet ensures that critical data is transmitted quickly and accurately, enabling precise control over manufacturing operations.

2. Device Interoperability: Profinet's standardization ensures compatibility between devices from different manufacturers, promoting seamless integration. This means that companies can choose the best devices for their specific needs without worrying about compatibility issues. It also simplifies system upgrades and expansions, as new devices can easily be integrated into the existing Profinet network.

3. Scalability: Profinet supports the easy expansion of the network, accommodating the addition of new devices without significant reconfiguration. This scalability is essential in dynamic industrial environments where production lines may need to be modified or expanded to meet changing demands. Profinet's flexibility allows for the seamless integration of new devices, minimizing downtime and disruption.

4. Redundancy: Profinet offers redundancy mechanisms that enhance system reliability, ensuring uninterrupted operation. Redundancy features such as device redundancy, network redundancy, and path redundancy provide fault tolerance and failover capabilities. This means that even if a device or network component fails, the Profinet system can automatically switch to a backup, minimizing downtime and maintaining continuous operation.

5. Security: Profinet incorporates robust security measures, protecting industrial networks from unauthorized access and cyber threats. With the increasing risk of cyberattacks on industrial systems, Profinet's security features are of utmost importance. These features include authentication, encryption, and access control, ensuring that only authorized personnel can access and manipulate the Profinet network.

By understanding the technical aspects and key features of Profinet, businesses can harness its capabilities to optimize their industrial processes, improve efficiency, and ensure the reliability and security of their networks.