PROFINET - A strong driver

Years ago, the term "drive engineering' referred to the use of frequency converters or servo amplifiers to control a motor according to a speed setpoint. The motor, converter, sensor, and regulator were components of the drive, while the controller was used only for the setpoint setting and actual value control. Safety functions and other additional functions had to be implemented using separate monitoring systems.

With the introduction of PROFIBUS for fieldbus communication and the development of PROFIdrive as a scalable device profile for drives, everything was made easier: signals of distributed inputs/outputs could be read in to the controller or output from the controller cyclically. Moreover, the acyclic communication functionality introduced subsequently eliminated the need for a separate parameter assignment and commissioning interface. Finally, the direct data exchange functionality replaced the interface between the drives with a single interface on the drive.

When the PROFIdrive, PROFIsafe, and PROFIenergy profiles were implemented jointly, it was possible to combine conventional drive functions with additional applications from safety engineering and energy management. Today, the controller level contains not only the drive controller but also the controllers for energy efficiency and safety. The drive itself contains not only the drive functions but also the energy management and safety engineering functionalities. The drive thus becomes a platform for various automation functions.

However, fieldbus systems based on different bus technologies such as PROFIBUS are still used at the level of the drives and field devices. Here, special systems can still occasionally be found for sequence and drive controls.

However, it is more and more common to find Industrial Ethernet-based systems within the drive level. The PROFIdrive profile, which covers all applications by virtue of its application classes, clears the way for drive manufacturers to take devices previously equipped with PROFIdrive and operate them with PROFINET in the future. PROFINET's scalable cycle times extend down to 31.25us and below - and with exact deterministic behavior. This meets the requirement of the most demanding drive engineering and motion control applications. Communication via PROFINET is deterministic with a jitter

The openness of PROFINET forms the basis for an integrated, uniform automation network in machines and plants with the additional option to connect standard Ethernet devices.

Support for getting started

An economical and easy approach for implementing the PROFIdrive profile is available for device manufacturers. Under the supervision of PI, well-known manufacturers of drive devices and technology components have established a community project "Reference implementation of Profidrive profile'. One goal of the project is to support drive manufacturers by providing them with source code for a standard PROFIdrive implementation free of charge as well as help in integrating the source code all the way to device certification. This will enable device manufacturers to implement PROFIdrive much more quickly and cost effectively.

Participating manufacturers of technology components and development kits are integrating this source code into their products, and can thus provide additional support for device manufacturers.

For plant and machine owners, the switch from PROFIBUS to PROFINET must be as easy as possible. Starting with Version 4.0 of the PROFIdrive drive profile published in 2005, the profile can be used with PROFIBUS as well as with PROFINET without any reprogramming of the application. This advance meets the machine building industry's demand for an easy, low-cost way of operating drives on both communication systems without having to change the profile implementation. This dual use is possible because the architecture of PROFIdrive draws a strict distinction between the communication-independent functions (primarily the application) and the communication system used. This enables an application to be run with PROFIBUS as well as PROFINET.

For further information about PROFIBUS, PROFINET, PROFIdrive and PROFIenergy, go to www.uk.profibus.com/.