Signalling & Communications, Technology and IT

Applying tried and tested industrial automation technology to railway systems

Automation technology firm Pilz says control systems from industry are possible options for the modernisation of infrastructure on the network.

Existing signalling and control technology in the rail transport industry, particularly on regional lines, is largely based on classic signal box technology. But Pilz says automation systems like its PSS 4000-R can help to significantly reduce the cost pools that have so far dominated in purchasing, engineering, operation and servicing.

Signal and control solutions in rail transport have so far been largely proprietary: the technologies have been designed, developed and manufactured specifically for use in rail transport.

Normative requirements, project specific features and a limited number of options for standardisation are cost-related factors in today’s applications. Even today, classic relay technology with positive-guided contacts is still widely used in railway and signal engineering.

As part of modernisation measures, however, Pilz says the trend is now towards replacing wearing, cable-intensive hardware with powerful software.

Safety and economy complement each other: given their widespread availability in the industrial environment and the use of standardised and hence proven industrial components, programmable logic controllers (PLCs) such as those used in industry, e.g. for mechanical engineering, are characterised by lower acquisition costs. Software tools simplify and reduce the configuration work, improve diagnostic options and facilitate maintenance and repair.

SIL 4 capability: the automation system

PSS 4000-R Pilz developed the automation system PSS 4000 in accordance with EN 61508 for industrial automation applications. To meet the specific requirements of rail transport, Pilz developed special modules with an –R (Railway) in the type description.

The PSS 4000-R systems are designed to be robust enough to withstand the electromagnetic interference, extreme temperatures and mechanical load that typically occur in a railway environment.

The PSS 4000-R has railway-specific safety approvals as a product feature, making the automation system SIL 4-capable across the whole application.

The rail solution PSS 4000-R comprises a number of function modules: Safe PLCs, I/O devices and various I/O modules for safety and automation functions are available as hardware components.

Devices communicate with each other via the real-time Ethernet communication system SafetyNET p, based on 10/100 BASE-T. TCP/IP, Modbus/TCP and UDP raw data, among others, can be exchanged with other devices parallel to the safety protocol. SafetyNET p can be used on standardised network components such as Ethernet switches or DSL modems, thus offering a high degree of freedom in terms of extension and topology. The latest expansion stage also allows the flexible RaSTA protocol to be used.

User-friendly programming

Pilz says its software platform PAS4000 can help operators create, configure and set the parameters for a safety-related application, and download that to the control system.

The software is responsible for creating and processing an application program, which includes reading in the digital and analogue process signals, logical and chronological processing of these signals in the logic unit, outputting digital and analogue process signals to control the process and transferring safety-relevant data via SafetyNET p.

Flexibility allows for variety of applications

Pilz says the openness and flexibility of this system has seen the PSS 4000 automation system used not only in classic mechanical engineering, but in car production, the chemical industry, on cable cars, dockside cranes and sluice systems.

For railways, the certified -R modules can be used in a variety of applications with different safety integrity levels. These include control or monitoring functions in signalling systems, such as monitoring signals at level crossings, control and safety technology or signal box connection, control functions of rolling stock and track laying machinery.

Modernisation during ongoing operation

Pilz says the PSS 4000-R automation can facilitate the staggered modernisation of railway control: measures can be implemented step by step and selectively.

The entire electronic periphery, comprising signalling, control and communication technology as well as the cabling between the control cabinets, remains untouched when the modules are installed, meaning the automation system also fulfils the role of an interface between the old control boxes.

The automation system PSS 4000-R is used in Europe to protect barriered and unbarriered level crossings, handling control and safety functions along the Golden Pass line in Switzerland, for instance, and neuralgic station nodes of the metro system in the Belgian city of Antwerp.

Together with DB Netz and Pilz partner Thales, Pilz has already realised projects for SPZA (memory-programmable central block adaptation) geared towards developing a safe platform for control tasks. The PSS 4000-R is capable of efficiently replacing obsolete relay-based signal box technology.

Contact: R.Stevenson (at)