The aim of the project: SCCGW-MS module to become a part of SML300Z supply operation environment of Alstom SpA.
The SCCGW-MS module is designed to become an interface between the SCC and the static station equipment based on the SML300Z CLC for remote non vital control management.

Besides, the SCCGW-MS operates as the communication and protocol adaptor necessary to interface the SCC with the VMMI-ERTMS module in regard to the information about the Train Number and the Authority State. These messages are used by the VMMI-ERTMS for displaying information about transit of trains and about the status of connection with the adjacent system.

The SCCGW-MS is designed as a "generic product", therefore it does not refer to any specific application but is capable to manage, if appropriately configured, all those facilities where the SML300Z must interfaced with the external SCC system.
This “configurability” feature concerns not only a specific plant but also the functionalities that the module must fulfill. In particular, the SCCGW-MS can be configured to perform:

• the only interface service between CLC system and SCC relatively to commands and controls,
• the only interface service between SCC and VMMI-ERTMS for protocol conversion and for forwarding of message regarding a Train number and an Entity states,
• both of the above at the same time.
• As of its collocation, the unit is placed between CNET network and a local Ethernet (responsible for a connection to the SCC Peripheral Post)

The connection with the SCC is established via TCP/IP protocol.
The communication protocol used between the SCC and the SCCGW-MS is provided by RFI. The module is able to communicate with the SCC systems, that supply the RFI, or with other systems providing some different delivery that implement the same protocol.
The communication with the CLC-VMMI ERTMS and the SDM-IS is established through CNET network. The connection used towards the CLC and the VMMI-ERTMS is UDP/IP.

In order to meet availability requirements, it is necessary to implement one unit composed of two sections in a hot stock (respectively: SCCGW- MS N and SCCGW-MS R), that would be physically separated and independently powered. Both would work “by event”, performing, thus, the unit functions at a minor/inessential time whether compared to real dynamics of application protocols.

Each section, N and R, is connected to CNET and to the SCC network via a redundant physical link. Another redundant physical connection between sections allows the internal status data exchange and maintains possibility of ” hot backup”. One of the two sections can be running (“in service”) while the other is "standby"; in any case, as the first section ends start-up, it must advance in a running state automatically, without any inclusion.

In hardware terms, the two sections, N and R, are identical to each other and use the same software process and the same configuration data. To distinguish N from R, a hardware key located in N section is used.

With regard to connections to CNET and to the SCC, both sections are always connected to networks, both in transmission and in reception. Only the running section, however, is enabled for transmission.

N section differs from R section as it is being the "master" in the management of hot redundancy mechanisms.

Integrity Level: according to the rules established by CENELEC EN 50128, the integrity level applicable to SCCGW is SIL0-MS, as the protocols and process information treated do not have security features.

Hardware Features: SCCGW-MS uses a HW COTS board based on Intel Pentium M processor; this board is provided with three standard Gigabit Ethernet network ports.
In addition, through an add-on Quad-Ethernet board, the PMC SCCGW-MS Controller is equipped with four additional Fast Ethernet ports used in pairs, this allows interfacing to CNET redundant network and towards the SCC. SCCGW-MS is installed on the VxWorks 5.5.1 Wind River Operating System.

The architecture of the module is not limited by the adoption of a specific board but is open to different boards, in accordance with the processing needs of each system and with the evolution of the business hardware.

The software development activities requires the usage of the following programming languages:

• ANSI-C without syntax restrictions for the development of SIL0 routine on embedded platforms that perform VMMI-ERTMS
• Minimal-C ANSI-C language with restrictions imposed by the documents for the development of SIL4 routine on embedded platform which realizes VMMI-ERTMS (IPA and VMMIMAIN board assembly)
• Visual C++ 6.0
• Languages such as simulators and test programs, to develop applications outside VMMI ERTMS platform
• Borland C++ Builder 5.0
• Perl DOS batch language to create scripts that automate software production phases
• UML Notation to describe the software architecture

The software development of SIL0 applications is based on VxWorks (version 5.4.2 and updates) and on "COTS" operating system (by Wind River).

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