IoT Communication Protocol – PROFINET

Overview

PROFINET, introduced by PROFIBUS International (PI), is a new generation of automation bus standards based on Industrial Ethernet technology. As an Ethernet-based technology, it shares some characteristics with standard Ethernet, such as full-duplex operation and support for various topologies, with speeds reaching 100 Mbps or 1 Gbps. Additionally, it possesses unique features, including: real-time data exchange capability, making it a Real-Time Ethernet; compatibility with standard Ethernet, allowing for integrated networking; and seamless integration of existing fieldbus systems through proxy mechanisms.

PROFINET provides a complete network solution for the automation communication field, encompassing current hot topics in automation such as Real-Time Ethernet, motion control, distributed automation, functional safety, and network security. As a cross-vendor technology, it is fully compatible with Industrial Ethernet and existing fieldbus (e.g., PROFIBUS) technologies. PROFINET is fully compatible with office Ethernet and utilizes all its functionalities. However, differences exist; office Ethernet cannot provide the real-time performance required for industrial automation. Office Ethernet is also less capable of withstanding harsh industrial environments.

What is PROFIBUS

The advantages of fieldbus include the ability to connect multiple devices via a single cable or "bus." This single factor alone can reduce design, engineering, commissioning, and maintenance costs by up to 40%. The higher accuracy of "digitalization" also means significant improvements in production speed and quality, while better diagnostics enable fieldbus-connected production lines to benefit from advanced asset management technologies. Fieldbus can also provide the real-time performance required by current automation environments.
PROFIBUS is the world's most widely used fieldbus. It was first promoted in 1989 by the BMBF (German Federal Ministry of Education and Research), then used by Siemens, and standardized according to IEC 61158. It is supported by over 1400 equipment suppliers worldwide. A single standardized approach means users have a wide choice of vendors and products, factors that encourage higher performance and lower costs. Plants supporting fieldbus can also provide more and better data to monitoring systems, supporting improved management strategies across the entire enterprise. PROFIBUS is the protocol standard for fieldbus communication in automation technology.

Main Features of PROFINET

1. With its integrated, Ethernet-based communication, PROFINET meets a wide range of requirements, from data-intensive parameter assignment to extremely fast I/O data transfer. Thus, PROFINET enables real-time automation and provides a direct interface to the IT level.
2. PROFINET is a "switched" network with a transmission rate of 100 Mbps when full-duplex connections exist. PROFINET is 100% compatible with Ethernet according to IEEE standards and adapts to existing plant situations thanks to its flexible line, ring, and star topologies, as well as copper and fiber optic cable solutions. PROFINET networks can adapt to the communication needs of the application. PROFINET saves on expensive custom solutions and enables wireless communication with WLAN and Bluetooth.
3. In all applications, communication occurs over the same cable, from simple control tasks to demanding motion control applications. For high-precision closed-loop control tasks, time-critical process data with a jitter of 1μs can be transmitted deterministically and synchronously.
4. PROFINET integrates automatic response redundancy solutions and intelligent diagnostic concepts. Acyclic diagnostic data transmission provides important information about network and device status, including the display of network topology. Defined concepts for media and system redundancy significantly increase plant availability.
5. The proven PROFIsafe safety technology from PROFIBUS is also available for PROFINET. The ability to use the same cable for standard and safety-related communication saves on equipment, engineering, and setup.
6. Since its introduction in 2004, PROFINET technology has been used by numerous companies across all industrial sectors—whether in combination with fieldbus systems like INTERBUS or as a standalone solution.

Development History

• PI (PROFIBUS International) was founded, with its roots tracing back to the beginning of PROFIBUS in 1987.
• In 2002, PROFINET CBA (Component Based Automation) became part of the international standards IEC 61158 / IEC 61784-1. The basic idea behind Profinet CBA is that in many cases, an entire automation system can be divided into autonomously operating—and thus manageable—subsystems.
• In 2003, the first Profinet IO (IO = Input/Output) was released. The application interface of Profibus DP (Decentralized Periphery), which was successful in the market, was supplemented by current protocols from the Internet.
• In 2004, an extension with synchronous transmission followed, making Profinet IO suitable for motion control applications.
• In 2006, Profinet IO became part of the international standard IEC 61158 / IEC 61784-2.
• In 2019, the specification for Profinet with TSN (Time-Sensitive Networking) was completed. These standards define time-sensitive mechanisms for transmitting data over deterministic Ethernet.

PI (PROFIBUS International) is the oldest and largest fieldbus organization, currently with 1400 members. PI consists of 25 regional PI associations (RPAs) worldwide, with 32 competence centers and 7 certified test laboratories. In addition to PROFINET, PI also supports PROFIBUS, which has the largest installed base of fieldbus nodes.

Protocol Architecture

PROFINET Communication Channels

In our daily work communication, we have different methods. One type is when we work closely with peers on a project; we understand each other's current context well, so our communication might involve brief messages or emails. However, if we are dealing with colleagues two levels up or from other departments, we may not know what the other is doing, so our communication needs a subject and must contain a lot of such background information and materials.

Similar to human communication, PROFINET has two different communication channels: one for communicating with peers who share some common "context" (RT), and another for communicating with those who share less "context" (NRT).

Real-Time (RT) Channel: Introduces a software-based real-time approach and reduces cycle times to approximately 10ms.

Non-Real-Time (NRT) Channel: Provides access to PROFIBUS via a proxy, bridging Ethernet and PROFIBUS by invoking TCP/IP's Remote Procedure Call. Its cycle time is about 100 ms and is mainly used for parameter data and acyclic I/O. Typical applications include infrastructure and building automation.

Isochronous Real-Time (IRT) Channel: This is a synchronous real-time technology that requires special hardware to reduce cycle times to below 1 ms, providing sufficient performance for motion control operations on a real-time Industrial Ethernet.

PROFINET Device Types

Related Resources

• PROFIBUS & PROFINET International (PI)
• PROFINET Technology Page
• PROFIBUS International
• PROFINET University
• PROFIsafe web portal
• p-net – An Open-Source PROFINET Device Stack
• PROFINET System Description and Application (PDF)