Railway communication

Embedded Safety and Security Interface

The Embedded Safety and Security Interface (ESSI) is to be developed as a device ensuring safety and security communication among applications in a distributed control system via an open transmission environment such as the Internet or WiFi.

Each ESSI device has two communication interfaces: a local communications interface providing N channels and an open communication interface providing M channels. ESSI devices are used in pairs to guarantee safe and secure communication between local and remote applications. The local ESSI device receives messages sent by applications to the N channels of its local communication interface, but does not handle the messages directly; instead, it handles bytes in the case of serial channels or frames in the case of Ethernet channels. This means that the ESSI is transparent for message transfer. The ESSI assembles received bytes/frames into packets that are sent simultaneously to M channels of its open communication interface. The remote ESSI device receives these packets, disassembles them, and distributes their content to the channels of its local communication interface, which correspond to the channels of the source ESSI. The application running in the destination end device makes up the messages from data received on each of its N channels and evaluates the validity.

The development must follow the requirements of the railway application standards EN 50129, EN 50128 and EN 50159 for the highest Safety Integrity Level (SIL 4).

Image: Embedded Safety and Security Interface (ESSI)