Starting in the IT sector, Industrial Ethernet technology has developed into a platform with efficient system integration. Increasingly users wanted PROFIBUS installations that offered wireless and fail-safe communication; more than one master in the same bus section; very high transmission rate over long distances, without separate repeaters or having to worry about speed, adaptation, reflection, collision; transmission of large volumes of data via the same cable; easy energy management; and more.
PROFINET came about as the logical consequence of technological evolution and the development work of PI: the umbrella organisation for PROFIBUS and PROFINET. It is the newer standard, which combines the advantages of both worlds. PROFINET is established and accepted around the world, with almost 13 million installed nodes in a wide variety of industries and sectors.
There are good reasons for this: in addition to existing PROFIBUS functions, PROFINET also provides a range of new properties, opening up options and advantages that aid engineers. For example, redundant, highly available ring topologies without additional switches using the Media Redundancy Protocol (MRP) or wireless communication (also fail-safe using the known PROFIsafe profile) between plant units and/or HMI devices.
The Shared Device function also allows devices or drives to be connected to several controllers, making expansions easier and more cost-effective. The I-Device function turns a PN-capable controller into both an intelligent controller and device, communicating like a controller with lower-level devices on the one hand and with higher-level or central controllers on the other.
Various automation components, including robots, communicate exclusively via PROFINET in two of the world’s largest and most modern factories for the manufacture of solar modules. It this case, it was not the size of the network that was the deciding factor, but the integration and performance.
Driven by the increasing requirements of production automation, the number of components with PROFINET functionality is growing as more manufacturers get on board. PI and the technology drivers from the automation industry promote the development of new PROFINET devices, for example with development kits and support.
The number of PROFINET-capable devices is rapidly growing and has long supported a variety of automation structures in industries, such as food and beverage, steel production, printing and logistics.
Siemens’ PROFINET portfolio also provides everything for integrated solutions. Encompassing, amongst others, PLC and motion control systems, IO devices, drives, and tailored network security technology.
The entry to the PROFINET world does not bring with it any insurmountable technical requirements and opens up options for cost optimisation in the overall consideration.
Engineering is implemented using the same tools as for PROFIBUS, based on SIMATIC Step 7 Classic or TIA Portal, and it does not require any in-depth IT expertise. The procedures are known, which means that no training or familiarisation is needed. It is not necessary to change the user program when switching from PROFIBUS to PROFINET.
For connecting other fieldbus systems (eg CAN bus, INTERBUS, etc), there are a number of proxies, which map the fieldbus on PROFINET. These are precisely defined and standardised in the PROFINET specifications, so there are no complex individual solutions.
It is also possible to use PROFIBUS components on PROFINET-based machines, in the event that individual PROFIBUS DP slaves are not yet available in the PROFINET version. There are various options for this on the market, such as special gateways for actuators and sensors.
Even if PROFIBUS has not reached its limits from a technological standpoint and no further developments are expected, the fieldbus system, and its components, will still be available in the future.
Developments and innovations are primarily aimed at PROFINET technology. PROFINET will be the standard interface for new components, but PROFIBUS will at least be an option, for example via special communication modules or device variants.
Compare to benefit
One decisive advantage of PROFINET is its higher performance, primarily with regard to the number of nodes, transmission rate, and diagnostics. The size of networks is nearly unlimited. PROFINET’s speed of 100 Mbit/s in full duplex mode with parallel communication via switches is much faster than PROFIBUS’ 12 Mbit/s.
The two PROFINET-supported real-time transmission modes RT (real-time) and IRT (isochronous real-time) with isochronous mode and their deterministic cycle times allow use in highly dynamic applications, including isochronous motion control applications such as distributed drive links with very short cycle times.
This is only possible using PROFINET and it easily satisfies the requirements of practically every application in use today. With cycle times down to 31.25µs, the PROFINET standard provides considerable performance reserves for even higher requirements. The result of the increased control accuracy is more consistent product quality and/or output.
Expanded diagnostics capabilities which can be used locally and via the Internet and intranet simplify commissioning and make a considerable contribution to keeping the availability of the machine, systems, and factories at the maximum level. This, in turn, generally means increased productivity.
It is recommended that users compare the individual requirements of each pending automation project to the multifaceted solution options of PROFINET and then make a decision. In most cases, the advantages of the new technology will predominate – even for small-scale projects.
Transition strategy
Using a step-by-step strategy, the operating requirements can be ideally taken into consideration. In the simplest scenario, the existing controller is replaced by a higher-level controller with a PROFINET interface, the GSDML files of the PN devices are updated in HW Config, the main modules of the distributed I/O are exchanged in the field, and the plant units are networked with each other via a PROFINET cable.
Network security under control
The integrated vertical openness, from the field level to the control level, requires specific measures for protecting against unauthorised access to the automation level. These measures are generally already known and come automatically along due to the use of Ethernet.
Many of the components that are available for Industrial Ethernet can also be used in PROFINET architectures, for example, various versions of the Scalance family of switches from Siemens (managed/unmanaged) and security modules for all requirements. These devices can largely be automated and configured from a central, remote location. This means that after a replacement they become available again in minimal time.
The time is now
PROFINET is easy, efficient, powerful, and flexible. It is already established in many applications and the number of components is constantly growing – and thanks to this, the technology has long been used in practice.
The earlier that users switch to PROFINET, the sooner it is possible to get the benefit from the many advantages. The manufacturers provide a wide range of support during the transition, from technical consulting and detailed documentation and guidelines, to in-depth training and practical application support.
