1. Executive Summary & Standards Compliance

The RBC <-> Interlocking (IXL / CBI) interface governs the vital, fail-safe communication between the wayside Computer-Based Interlocking and the Radio Block Centre (RBC) in an ERTMS/ETCS Level 2 railway signaling environment.

Applicable Standards:

CENELEC EN 50128: Railway applications - Software for railway control and protection systems (SIL 4). CENELEC EN 50159: Railway applications - Safety-related communication in transmission systems (Category 1 & 2 closed/open networks). EULYNX Baseline 3 / 4: SCI-RBC (Standard Communication Interface for Radio Block Centre). UNISIG Subset-098 / Subset-099: RBC System & Interface Requirements.

Note

Simulation Testbed Status (Simplified Mode): In the current test simulator environment (RBC_Test_Sim_IL / RBC_Test_Sim_Core), route allocations are injected using the simplified ROUTE_ADD command (and TrainPositionInRoute feedback in extended mode) as documented in RBC_Test_Env/doc/design/SIM_INTERFACES.dox. This simplified interface maps directly into the formal EULYNX/SCI-RBC vital structures detailed below.

2. Safety Layer Protocol Architecture (EN 50159 / SIL 4)

Because movement authorities directly depend on route integrity, all messages exchanged between IXL and RBC are encapsulated in a Vital Safety Envelope:

$$\text{Safety Envelope} =\text{NID_IXL (32b)}, \text{NID_RBC (16b)}, \text{SEQ_NUM (32b)}, \text{TIMESTAMP_MS (64b)}, \text{MSG_TYPE (8b)}, \text{PAYLOAD}, \text{CRC64_VITAL (64b)}