The Pfänder tunnel is one of the most important motorway connections between Germany and Austria. Originally built with one tube providing one traffic lane in each direction, a second tube with two further lanes has been opened in 2013. The construction of the second tube involved also a modernization of the supervisory control system for the entire tunnel and the integration with the tunnel control center. This upgrade to state-of-the-art technology is based on PROFIBUS DP and has been performed by evon GmbH.
The requirements included the integration of all field devices into the communication sys-tem and the implementation of a redundancy solution. In view of the long distances to be covered in the overall facility and the huge data volumes to be transmitted, evon decided to employ the PROFIBUS DP Master Stack from Softing Industrial Automation Connection of the various field devices is based on PROFIBUS DP technology with baud rates of 1.5 MBaud and 93.87 kBaud in the fieldbus, respectively. The various PROFIBUS configurations use 129 PROFIBUS DP slaves with cycle times are < 20 milliseconds. The requirement for highest availability and stability of the entire supervisory control system to ensure reliable 24/7 tunnel control resulted in a redundancy solution with two PROFIBUS DP Masters. This challenging application was realized by using the PROFIBUS DP Master and PCI interface card from Softing. Using two PROFIBUS DP Masters and switching between the active and the backup master alone does not provide the required redundancy functionality yet. It is also necessary to include all field devices in such a way that switching over to the other PROFIBUS-DP Master will not result in a default restart of the PROFIBUS DP slaves. This requirement could also be met by the solution as described.
As a result, PROFIBUS DP together with the DP interface technology from the PI member company Softing could be successfully be integrated into the existing Pfänder tunnel su-pervisory and control center. This seamless interfacing solution can certainly applied to similar tunnel projects by accessing PROFIBUS via small compact controllers, PC interface cards, or also via PROFIBUS remote interfaces in an Ethernet network.