scope:

All SSI Interlocking MPMs.

Purpose

This NB is to bring attention to a requirement of RT/E/C/17901, to ensure that all three Interlocking MPMs within a Central Interlocking are of the same type and modification state, and running the same version of main, trackside communications, and internal communications software. This is to avoid possible timing issues that may otherwise develop in the timing critical triplicated system.