The USA's first airport to have computerized airfield lighting uses PROFIBUS communications. Boston's Logan, established in 1923, has always been an airport of 'firsts'. Recent upgrades make use of latest technology, innovative software solutions, improved programmable logic controllers (PLCs), and better bus technology. The system was designed by Edwards and Kelcey.
S7-400 PLCs replaced older units. All equipment is housed in a secured area of the airport property, referred to as "The Vault", and this also houses two redundant PLCs that are at the heart of control. Four levels of redundancy are built in: controllers; PROFIBUS communications; PROFIBUS I/O; power sources. OLMs allow Ethernet to be used and fiber cabling uses a self-healing 'spanning-tree' architecture for redundancy. Also, if an OLM module fails, the PROFIBUS I/O module has a copper connection to an adjacent OLM that takes over the defective module's responsibility.
The PROFIBUS wiring and the fiber were laid down inside the existing metal raceway. The bright purple color of the PROFIBUS cable makes PROFIBUS cables highly visible and underscores the fact that it barely takes up any space in the channel. Its weight is negligible and the raceway is now free for other expansion projects.
The use of PROFIBUS provides extremely fast response times. The built-in features allow easy configuration, and additional drops can be added easily. PROFIBUS also greatly simplifies the time needed for installing cabling.