What is PI?

PI was formerly know as PROFIBUS International. It is the umbrella organization responsible for the PROFIBUS protocol and its promotion and support across the world via a network of Regional PI Associations. When PROFINET, PI's Industrial Ethernet solution, was launched, PROFIBUS International was re-named 'PI' (PROFIBUS and PROFINET International).

Is it necessary to have GSD or other similar documents when the products of the third vendor are to be integrated?

The integration of third party devices into PROFINET IO is identical to the concept used in PROFIBUS. In both systems GSD files are used. However in PROFINET IO these files are XML-based and are know as GSDML files.

What is a proxy?

It's a 'black box' for linking sub-networks such as PROFIBUS, Interbus (and most other popular fieldbuses, plus some other protocols) into a PROFINET system. The proxy solution is unique to PROFINET and it ensures that existing investments in fieldbus equipment and, perhaps more importantly, skills can be retained when migrating. A proxy is much more than a simple gateway - it is a PROFINET slave combined with a master for the sub-network, so the sub-network performs as if it's part of the main network. This ensures full transparency between the two.

How many PROFIBUS devices can be connected to a proxy?

In the PROFINET standard there is no limitation on the number of PROFIBUS devices which can be connected to a proxy. One vendor's product for example supports up to 64 PROFIBUS slaves.

Does PROFINET also function with other operating systems, such as Linux and Java?

The PROFINET concept is independent of the operating system. PROFINET stations can be implemented in any form provided that they comply with the PROFINET specification.

Extract from IEEE 11/2000: 'The runtime software was developed under the stringent requirement of operating system neutrality, to enable easy integration of the PROFINET core software in a wide range of embedded PLCs and systems by adapting it to the individual system - a specific operating system is not a prerequisite.'

Can PROFINET with IRT use ordinary Ethernet switches?

PROFINET in its TCP/IP and RT modes can. However, IRT applications require the support of an ASIC to handle time scheduling and synchronization. This is not unusual among Industrial Ethernets

Regarding the IEEE 802.3-based PROFINET, how can I ensure the real time functionality of IRT without collisions?

PROFINET uses switches as network components with full duplex communication functionality, so no collisions occur in a PROFINET network. In motion control applications, an ASIC switch ensures the handling of the IRT telegrams in pre-defined time slots.

Can PROFINET IO devices be related to one specific PROFINET controller?

Unlike PROFIBUS, a PROFINET IO-Device can be allocated to several PROFINET IO-Controllers.

Are there any limitations regarding the length of the cabling?

One of the advantages of PROFINET is that it enables the creation of flexible network structures. The length, speed and topology depend on the network components you choose for your network. For example, in case of fiber optic cabling, with integrated interfaces you can reach up to 300 m between devices. With external components fiber optic distances of up to 26km are possible depending on the type of fiber optic being used and the vendors. In an electrical network the maximum distance between any two devices is 100m.

What's the difference between real time data and acyclic data?

Real time telegrams are telegrams that have the label 0x8892 in the standard Ethernet frame header. This is independent of whether the communication is cyclic or acyclic. Both real time and non real time communication are simultaneously possible on a PROFINET network.

How do I make the transition from traditional Industrial Ethernet to PROFINET?

PROFINET is based on Industrial Ethernet which has been used in plants for many years at cell levels and higher. PROFINET brings Industrial Ethernet down to the field level so that you can directly interconnect to field devices. So the same network infrastructure components (switches, cables, connectors) can still be used today with PROFINET. Many of the same network tools and techniques remain the same also. In PROFINET, many of the strategies and techniques common in the PROFIBUS world can be utilized. Migration is also very easy, with no need to obsolete existing equipment or skills. Anyone moving to a PROFINET future will find many similarities with the world of fieldbus.

What's the biggest difference between the Industrial Ethernet and PROFINET?

PROFINET IO brings Industrial Ethernet down to the field level and introduces the concept of real time operations. PROFINET also allows standard TCP/IP communications to take place AND it offers the high performance real time needed for motion control. Functional Safety can also be deployed on a PROFINET network. Overall, the capabilities of PROFINET are broader and more flexible than PROFIBUS, especially when considered in an enterprise-wide context.

Does PROFINET support redundancy?

Media redundancy is available for PROFINET. System redundancy is under development.

Is it necessary to use special PROFINET switches or can ordinary industrial Ethernet switches be used?

PROFINET uses ctandard Ethernet switches. Only IRT functionality for Motion Control requires ASIC support.

How is PROFINET handling real-time (RT) and non-real communication (NRT) on one network?

RT and NRT communication within one cycle are separated. RT communication always has the highest priority

What is the difference between PROFIBUS and PROFINET? Is there any independent interface?

PROFIBUS is a Fieldbus based communication system. PROFINET is an Ethernet based communication system offering an easier way to integrate automation systems into company-wide IT systems architectures like MES (Manufacturing Execution Systems) or ERP (Enterprise Resource Planning).

We are using an Ethernet controlled network that is connected to both Interbus and PROFIBUS. What is the interface?

PROFINET allows the seamless integration of underlying fieldbus systems using proxy technology (see above). This allows reduced costs for product development and engineering, and seamless data transfer between all networks.

What's the difference in terms of the application between PROFIBUS and PROFINET?

From the user's point of view there is little or no difference except that with PROFINET a much broader range of opportunities is open to him.

What role does the VLAN symbol in the Ethernet data frame play in PROFINET?

The VLAN symbol is always used in every RT frame. NRT Frames may use it. With the VLAN Tag it is possible to increase the priority of a frame to be sent. Normally it is enough to distinguish the priority with our Ethertype for RT (0x8892). But to ensure interoperability with older Ethernet switches we also use the VLAN Tag.

If existing devices have an Ethernet interface, is it still necessary to employ PROFINET?

Only the PROFINET software stack has to be integrated into the device. Usually this can be done by the device supplier.

How far is the transmission distance for PROFINET?

One of the advantages of PROFINET is that it enables the creation of flexible network structures. The length, speed and topology depend on the network components you choose. For example, in the case of fiber optics, with integrated interfaces you can reach up to 300 m between devices. With external components, fiber optic distances of up to 26km are possible depending on the type of fiber being used. In an electrical network the maximum distance between any two devices is 100m.

When PROFIBUS & Interbus are integrated into PROFINET, what kind of extra devices are needed?

Only one proxy device is needed for the integration of each fieldbus system such as PROFIBUS or Interbus into PROFINET.

When the IO point reaches over 200 in a power station, would the capacity of the switch limit network size?

200 IO points is no problem on a PROFINET network. One of the main advantages of PROFINET compared to PROFIBUS is that you can have more nodes on the network. Please note that any configuration with PROFIBUS can be realized with PROFINET, as far as the number of devices on the network is concerned. PROFINET uses switches as network components with full duplex communication functionality, so no collisions occur in a PROFINET network.

Is PROFINET applicable to Process Automation? What's its relationship with PROFIBUS?

PROFINET allows the simple integration of existing PROFIBUS PA applications in order to protect any investments you may have made. A proxy is used to link the two networks. In effect, PROFINET acts like a PROFIBUS DP network in process automation.

If I start a new project today, would you recommend PROFIBUS or PROFINET?

If you are happy with PROFIBUS as a solution today, then you can continue to use PROFIBUS. PROFIBUS will continue to be developed and supported for many years. If however you want to take advantage of the greater benefits of PROFINET (e.g. Wireless applications, high performance Motion Control , increased diagnostic particularly via the Web/email) then we suggest you look at PROFINET.

How can PROFINET be adapted to the current Microsoft developments (.NET)?

.NET is the Microsoft concept for future e-business applications and does not meet all the requirements of automation. COM/DCOM is well-proven in automation for communication applications (e.g. OPC). Current Microsoft concepts will be taken into account during any further development of PROFINET.

Is PROFINET a concept solely applicable to the field level?

No. PROFINET's capabilities make it ideal for use in applications ranging from management level right down to field level device level. It offers considerable flexibility both horizontally and vertically in an enterprise.

With PROFINET, is it always necessary to install two bus systems i.e. Ethernet & PROFIBUS?

Pure PROFINET solutions as well as combined PROFINET and PROFIBUS solutions are possible. The strengths of PROFINET lie in the integration of both bus systems in a common concept. The advantage is that in cases in which technical solutions do not exist for Ethernet, PROFIBUS can be used without the need to adapt the fieldbus protocol or field devices. An example of this would be motion control or safety-related applications.

Who supplies Engineering Tools for PROFINET?

The multi-vendor engineering model of PROFINET allows automation manufacturers to develop their own engineering tools that can be used to configure components and devices from different manufacturers.