DIN EN 50657/A1:2024-04

This European Standard specifies the process and technical requirements for the development of software for programmable electronic systems for rolling stock applications. This standard does not apply to software that: - is part of a signal-related device on the train (applications of CENEL Subcommittee SC 9XA); - contributes to operational functions of rolling stock and is separate from them. This European Standard applies exclusively to software and the interaction between software and the system to which the software belongs. This European Standard applies to safety-related and non-safety-related software, including, for example: - application programming; - operating systems; - supporting tools; - firmware. Application programming includes programming in high-level languages, machine languages, and special application languages (for example, PLC contact diagrams). The use of previously developed software and tools is also addressed in this European Standard. Such software may be used if the specific requirements in 7.3.4.7 and 6.5.4.16 for previously developed software and for tools in 6.7 are met. Software developed in accordance with a valid edition of EN 50128 is considered to be compliant with this standard. Software previously developed in accordance with any version of EN 50128 is also considered to be compliant and is not subject to the requirements for previously developed software. For SIL1-SIL4 software within the scope of this standard, the requirements contained in this European standard are equivalent to the SIL1-SIL4 software requirements of EN 50128:2011. This document has been derived from the signalling standard EN 50128 which in many cases was also applied in rolling stock applications. Subclause 1.6 ensures continuity in the application of the standards, that is software that has been developed in accordance with EN 50128 can still be re-used for new projects. This European standard takes into account that modern application design often uses software that is suitable as a basis for various applications. This software is then configured using application data to produce the executable software for the application. This European standard applies to such software. In addition, specific requirements for application data are specified. This European standard does not apply retroactively. It therefore applies primarily to new developments and, in its entirety, to existing systems only if they undergo major changes. For minor changes, only 9.2 shall apply. However, the application of this European Standard is recommended for the extension and maintenance of existing software. The applicable clauses of this software standard apply in addition to the applicable hardware standard (for example, EN 50129, EN 50155, EN 61508-2) also for programmable components (for example, FPGA and CPLD). Requirements of this software standard that are already covered by the applicable hardware standard do not need to be addressed again. This European standard does not apply if it is possible to comprehensively test the programmable logic for all possible input signals and internal logical states. The document contains changes to the "Scope", Clause 5 "Software management and organization", and Annex ZZ.