The standard is maintained and supported by Profibus and Profinet International, an umbrella organization headquartered in Karlsruhe, Germany.

IO-Controllers are typically a PLC, DCS, or IPC; whereas IO-Devices can be varied: I/O blocks, drives, sensors, or actuators.

The Profinet protocol is designed for the fast data exchange between Ethernet-based field devices and follows the provider-consumer model.

These ARs are used to define Communication Relations (CR) with different characteristics for the transfer of parameters, cyclic exchange of data and handling of alarms.

[1]: 4 The project engineering[1]: 5  [2] of an IO system is nearly identical to the Profibus in terms of "look and feel": Profinet is also increasingly being used in critical applications.

Profisafe[7] defines how safety-related devices (emergency stop buttons, light grids, overfill prevention devices, ...) communicate with safety controllers via Profinet in such a safe way that they can be used in safety-related automation tasks up to Safety Integrity Level 3 (SIL) according to IEC 61508, Performance Level "e" (PL) according to ISO 13849, or Category 4 according to EN 954-1.

They do not depend on error detection mechanisms of underlying transmission channels, and thus supports securing of whole communication paths, including backplanes inside controllers or remote I/O.

In the event of an error, the second IO-Controller can therefore take control of all IO-Devices without interruption by marking its output data as primary.

How the two IO-Controllers synchronize their tasks is not defined in Profinet and is implemented differently by the various manufacturers offering redundant control systems.

The Media Redundancy Protocol (MRP) allows the creation of a protocol-independent ring topology with a switching time of less than 50 ms.

[13] This concept is supported by organizational measures in the production plant within the framework of a security management system according to ISO 27001.

For a smooth interaction of the devices involved in an automation solution, they must correspond in their basic functions and services.

It was jointly developed by manufacturers and users in the 1990s and since then, in conjunction with Profibus and, from version 4.0, also with Profinet, it has covered the entire range from the simplest to the most demanding drive solutions.

This was requested in 2009 by the AIDA group of German automotive Manufacturers (Audi, BMW, Mercedes-Benz, Porsche and Volkswagen ) who wished to have a standardised way of actively managing energy usage in their plants.

High energy devices and sub-systems such as robots, lasers and even paint lines are the target for this profile, which will help reduce a plant's energy costs by intelligently switching the devices into 'sleep' modes to take account of production breaks, both foreseen (e.g. weekends and shut-downs) and unforeseen (e.g. breakdowns).

The Profinet AR life-cycle consists of address resolution, connection establishment, parameterization, process IO data exchange / alarm handling, and termination.

Likewise, the Link Layer Discovery Protocol (LLDP) for neighborhood detection including the extensions for Profinet must be supported by all Class B devices.

With these mechanisms, the topology of a Profinet IO network can be read out at any time and the status of the individual connections can be monitored.

To ensure that maximum Ethernet telegrams can still be passed through transparently, the green phase must be at least 125 μs long.

In order to achieve shorter cycle times down to 31.25 μs, the Ethernet telegrams of the green phase are optionally broken down into fragments.

In order to implement these bus cycles for bandwidth reservation, precise clock synchronization of all participating devices including the switches is required with a maximum deviation of 1 μs.

If several Profinet devices are connected in a line (daisy chain), it is possible to further optimise the cyclic data exchange with Dynamic Frame Packing (DFP).

The Time-Aware Shaper (TAS)[24] now specifies a clock pulse with which the individual queues are processed in a switch.

For class D (CC-D) devices, the hardware must support the required functionalities of Time-Sensitive Networking (TSN) according to IEEE standards.

Just one year later, the first specification of Component Based Automation (CBA) was published and presented at the Hanover Fair.

A planning tool loads these descriptions and allows the logical connections between the individual components to be created to implement a plant.

The basic idea behind Profinet CBA was that in many cases it is possible to divide an entire automation system into autonomously operating - and thus manageable - subsystems.

However, Profinet CBA does not find the expected acceptance in the market and will no longer be listed in the IEC 61784-1 standard from the 4th edition of 2014.

In the following year, the extension with isochronous transmission follows, which makes Profinet IO suitable for motion control applications.

In 2019, the specification for Profinet was completed with Time-Sensitive Networking (TSN),[32] thus introducing the CC-D conformance class.