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Reference project: communication server for subway door systems - increased security for subway passengers!

In Hong Kong, the platform edges of two subway lines are equipped with 1280 automatic door systems from Gilgen Door Systems AG. BBC Bircher Automation developed a communication server (PSC) for a platform screen door system on a robust PLC basis, which is the link between the platform and the control system.



Application area:

The new Shatin to Central Line (SCL), equipped with 560 of these door systems, will be opened in Hong Kong in 2020. The construction of the line takes place without public service. The other 720 door systems are retrofitted overnight as a retrofit in the Ma On Shan line, which has been in operation since 2004. The MTR operator guarantees 19 hours of train traffic 365 days per year and although a high train frequency with minimal intervals of up to 130 s is planned, the door system was designed for an operating time of 35 years.

Software development process:

Due to the long-term intensive cooperation, Gilgen Door Systems AG awarded the BBC Bircher Automation the order to fundamentally revise an existing software in order to continue to implement long-term, maintenance-friendly software with the new architecture. The software for static and dynamic test methods was designed on the basis of EN50128 (European standard for safety-relevant software for railways). The software development process was defined by the V-Modell. When implementing, the C programming language was used in compliance with the MISRA-C programming guideline, which aims to improve quality in terms of reliability and maintainability.

The module design documentation of each C function is done with Doxygen, which automatically generates HTML pages with dependency graphics from the source code.

The Cantata tool was used for the complex unit tests. A test had to be implemented for each individual C function. The use of the version control system Subversion brought many advantages in the traceability of changes as well as in the creation of versions.

The new development of the software was carried out strictly according to the stages of the V-Modell in the following steps: analysis with reviews, design with reviews, module design with reviews, coding, module test, software integration test, HW / SW integration test and requirement Test.

The extensive English documentation was reviewed by the customer Gilgen Door Systems AG and the MTR operator. Consistent traceability at all levels of the V-model was certified by BBC Bircher Automation through several customer audits by MTR.

Functionality / interfaces:

The communication server PSC contains various interfaces:

  • CAN Bus
  • IOs
  • Modbus RTU
  • Modbus TCP
  • RS485
  • OPC UA
  • FTP
  • USB

The core task of the PSC is to record the current status of the door system and report all critical conditions as alarms to the control system across all stations. At the same time the

The data and alarms are recorded in the retentive memory and in files and, if necessary, made available via OPC UA, FTP or USB in order to carry out a problem analysis. In order to carry out the maintenance of the three embedded systems per door comfortably and quickly, the firmware can be loaded using the central software download function.



  • B&R X20
  • CAN
  • OPC UA via Ethernet
  • Modbus Serial and TCP
  • File management
  • XML file for configuration
  • Read out and convert MHX files for
  • Firmware update
  • USB
  • Programming language C, Misra C
  • Unit test with Cantata
  • Documentation module with Doxygen
  • PLC project without global variables
  • Exchange of data via messages for data encapsulation
  • 3 layer software architecture (hardware, core, application)
  • Wrapper patterns, bridge patterns, container patterns, observers, data mapper patterns
  • EN50128 on SIL2

SIL (Safety Integrity Level)

Although the communication server PSC is classified as SILO, the project was realized based on the high SIL2 requirements according to EN50128. This is because Gilgen Door Systems AG applies the same safety requirements to all software components of the door system.


Overview of the PSC main data

  • Monitoring of the doors via CAN
  • Time synchronization of the doors via CAN
  • Monitoring of passenger identification via CAN
  • Monitoring of the platform screen door system via digital inputs
  • Reading in the data from the train control system
  • Local display of the states in the external visualization via OPC UA
  • Cross-station display of the states in the external control system via Modbus
  • Recording  the data in the retentive memory
  • Recording  the data in files
  • Provision of files via USB and FTP
  • Local display of the status with lamp indicators on digital outputs
  • Interface to the external maintenance program via OPC UA
  • Firmware update of the doors via central software download