Transporting people and particles

The Warsaw subway transporting people
The city of Warsaw, capital of Poland, first had plans to build a subway about 100 years ago. For many reasons, it took until the early 1990s until the first subway train traveled underneath the city in 1994. The planning and development were completed at the Faculty of Transport at the Technical University of Warsaw. A subway system transports millions of people at high speeds and in rapid succession during rush hour. The utmost safety and reliability of such a transport system are key requirements.

Figure 1

Figure 1, courtesy of Kontron, Germany, shows a VMEbus-controlled subway in Warsaw, Poland. The designers selected 3U VMEbus boards and systems from PEP Modular Computers (now a part of Kontron) for this purpose. Real-time transmission of data literally parallel to the rail tracks is executed via optical fiber cables using PROFIBUS protocol. A fiber optic Ethernet is used for a less critical services network. The system has been continuously enlarged and enhanced during the past 12 years. It has shown high reliability at extremely high Mean Time Between Failure (MTBF). After many years of cooperation between the University of Warsaw and Kontron East Europe, Kontron has taken over maintenance and installation. Both partners are still preparing new solutions for the subway and for the traditional railway systems. The most recent upgrade was in 2005; the next upgrade is planned for 2007.

There are two classes of systems that constitute the Warsaw subway control system. They are the Remote Control and Supervisory System and the Computer Interlocking System, one for each subway station. These systems fulfill SIL-4 requirements, the highest railway security level.

A typical system in one of the subway stations (for example, Plac Wilsona = Wilson Place) may have about 3,000 I/O points to manage in real time using OS-9. The initial installation between 1992 and 1994 included 11 subway stations and one dispatcher central system. The real-time fieldbus network PROFIBUS was the largest one worldwide at that time. The number of stations has grown, and some parts of the systems were upgraded (partially with 6U VME cards) during the past 12 years. In 2006-2007, five new subway stations will be added, initially including about 1,000 I/Os. The dispatcher center will get upgraded software without any need to change the hardware. Since the VMEbus is asynchronous, there is no need to replace complete systems if just one or two newer, higher-performance boards are needed within a system. This minimizes operational and investment cost over such a long period of usage. No custom boards or transmission equipment were needed.

During normal operation, the trains are controlled automatically. The operators can concentrate their attention on handling exceptional conditions, error reports, and short-term changes. The central computer receives new information at 660 ms intervals from all the subway stations. The entire system always runs in real time. No messages are sent or events logged after the event. The dispatcher central station system is duplicated at the depot. Fiber optic links are duplicated to provide alternate routes in case of technical problems. Fiber optic transmission was chosen to eliminate electromagnetic interference in copper lines from passing trains only an arm’s length away.

The Swiss Light Source transporting particles
The Swiss Light Source (SLS) was described in general terms in VMEbus Systems, August 2006. The FPGA cards mentioned in that issue were part of the VMEbus crates (subracks) that were planned, assembled, and delivered by Hytec Electronics Ltd., UK. Hytec delivered about 150 VMEbus systems using more than 800 VMEbus cards. Most of these cards are hot swappable and carry IP modules (ANSI/VITA 4).

The hot swap is fully VME64x compliant. Carrier cards and IP modules may be swapped out and in without powering down the crate. I/O connections are via rear transition boards, eliminating any cable connector removals during hot swap. The drivers, which support hot swap, were written for the EPICS software environment as used at PSI and in many other worldwide scientific applications.

Hytec supplies LabVIEW VI (Virtual Instrument) drivers for their VME carrier board VTR2535, which allows the capture of waveforms. These are transported to PC via the VME controller card VPI 13331. Up to eight channels may capture different waveforms, which can be superposed. Operating frequencies can be selected. Hardware or software triggers may be initiated. The VTR 2535 digitizer provides 10 MHz, 12-bit digitizing at 512 KB/channel. Read back of the selected range is possible. Separate pre- and post-trigger clock frequencies may be selected. Multiple frequency, single pass mode allows for digitizing at a programmed rate, which is then changed to another rate when triggered until a preset number of post-trigger samples have been taken. Separate pre- and post-trigger and multiple segment memory areas may be set.

For further information, e-mail Hermann at  hstrass@opensystems-publishing.com.