Audi uses decentralised I/O system for safety and automation

The head office of Audi AG in Ingolstadt in central Bavaria is the Audi Group's largest production site and Europe's second largest car plant. This is where the new Audi A4 will roll off the production line this year. It will be manufactured on two levels in the new A4 body plant, setting worldwide standards in car manufacturing. Part of the automated production lines consists of more than 200 high-speed rolling doors, which provide access to the individual production and assembly segments. The Hungarian Audi site in Gyr has already enjoyed very positive experiences with the decentralised, flexible I/O system PSSuniversal from Pilz. That is why the system is now also being used in Ingolstadt for complete management of the safety and non-safety-related signals that occur at the doors.

The investment in the new A4 body plant shows a clear commitment to the Ingolstadt site and is part of one of the largest investment programmes in the company's history: by 2019 more than one billion Euro will be invested here annually on average. More than 41,000 people now work in a total area of around 274 hectares (as of April 2015).

Car manufacturing is largely automated, like almost no other industrial sector. From component supply through to final assembly, robots and other automated handling systems perform a wide range of tasks. This is particularly true for the body plant. The new production hall uses over 200 high-speed machine protection doors from two different manufacturers to guarantee that parts are fed in and out safely and efficiently along the individual production and assembly modules. The high-speed doors are between 4m and 7m wide and open and close at a speed of up to 2.3m/s. They protect inlets and outlets from unauthorised access and effectively protect anyone in the surrounding area from potential hazards.

As previously at the Hungarian Audi site in Gyr, the machine protection doors were to be equipped with a compact, sophisticated Profinet-compatible interface. Once Audi had become familiar with the PSSuniversal as a reliable safety-related system, the decision was made to use the Pilz decentralised I/O system in Ingolstadt as well.

Safety and non-safety data

The certified Profinet interface is designed to meet the respective requirement of the relevant communication media, enabling the PSSuniversal decentralised I/O system to be incorporated seamlessly and safely into the existing plant structure. Profinet can be used to transfer real-time data, IT functions and safety-related I/O signals via a single cable. One particular advantage is that PSSuniversal's safety principle includes safety from the outset: only the head module represents the safety-related subscriber; it is the only place where the user has to make the necessary settings. There is no need to assign further sub-addresses; all safety-related addresses on the Profinet Master are used to the optimum. This simplifies and reduces the work involved for internal network administration, for example, and therefore reduces costs. Addresses are set once only in the head module; there is no need to set and manage addresses for individual I/O modules. PSSuniversal is fundamentally convincing with its technical simplicity, efficiency, openness and flexibility. The system requires little space in the control cabinet and is simple to install.

The PSSuniversal decentralised I/O system provides benefits wherever plants are distributed over a wide area. Users have an efficient, open and expandable system, whose modular structure does more than just meet the rigorous demands of the automotive industry. As PSSuniversal detects and processes safety-related as well as non-safety-related control signals, meaningful synergies are often the result: close dovetailing and partial processing of signals in situ reduce reaction times and increase plant availability. The merging of automation and safety functions produces savings during design, implementation and operation.

In the new production site, safe position messages such as 'Rolling doors closed' are implemented using Pilz PSENcode coded safety switches. Non-wearing safety components in accordance with EN ISO 13849-1 are required due to the switching frequencies and these devices have appropriate approval for use in the automotive industry.

The emergency stop functions on the door drives and all the safety sensors that monitor whether a door is actually closed are connected via safe I/O modules docked to the head module. Non-safety-related signals and messages are also connected to the head module via additional digital inputs and outputs. As the I/O modules for safety and automation can now be freely combined, without the strict separation that used to be customary between both systems, the respective input and output nodes can also be expanded flexibly.

Emergency shutdown of door drives

One particular advantage of the PSSuniversal decentralised I/O system is the safe, emergency stop shutdown of the door drives. These are controlled directly via two safe relay outputs. Via the bus system's digital inputs, the door control system can signal operational readiness, the current state of the respective door (open/closed), whether the crank handle is inserted and whether the emergency stop pushbutton or advance light beam device/closing edge has been operated. Signals from the bus system's digital outputs to the gate control system can initiate the opening or closing of a door, monitor the correct function of the closing process or also ensure that error messages are reset or acknowledged. Even the optional enable button on the feed doors is controlled via the inputs and outputs on the I/O system.

PSSuniversal enables a close relationship between safety and automation, allowing users to develop completely new concepts. In no way is safety compromised, no matter how high the level of automation may be. Absence of feedback is a matter of course, as is reliable separation via safety mechanisms, which rule out manipulation, whether deliberate or accidental.

Greater safety with integrated automation

With the Ethernet communication standard, PSSuniversal head modules with a Profinet interface open up new possibilities: in contrast to systems on which the safety technology has been installed retrospectively, PSSuniversal offers much greater safety with the same level of integrated automation. This is an advantage when it comes to handling the system, making it easier for users to work with the safety technology. Essentially the flexible I/O system is geared to the requirements of the respective application. Completely hybrid physical structures are just as possible as pure automation or safety applications.

In fact users do not need to pay for any additional hardware or components such as disconnection modules, special shielded cable or special EMC filters. That is because PSSuniversal was developed strictly to meet the needs of safety technology. Any connected periphery device is supplied separately; the use of supply modules means that independent supply groups are formed.

Efficiency gains

The use of the PSSuniversal decentralised I/O system makes commissioning, upgrades and servicing quicker and more efficient. The system stands for user-friendly configuration and a clear, structured design, including clear fault evaluation and diagnostics. PSSuniversal with Profinet connection can easily be connected to the higher-level control systems - defined by AIDA (Automation Initiative of German Domestic Automobile Manufacturers). The intuitive PSSuniversal Assistant configuration software is used to select the modules and configure the interface. PSSuniversal can be commissioned quickly using a special start-up tool. Initial cable and function tests can be carried out long before the plant or machine is built.

Pilz has already demonstrated in other Audi production sites that safety and automation can be reliably combined in one system. That is why it is now being used to an even greater extent in the new production hall in Ingolstadt. And the company will also use the sophisticated Pilz PSSuniversal decentralised I/O system when building a new production line for the Audi Q5 in Mexico.

Follow the link for more information about the Pilz PSSuniversal decentralised I/O system.