The Consolidation of the CERN Beam Interlock System

The Beam Interlock System (BIS) is a machine protection system that provides essential interlock control throughout the CERN accelerator complex. The current BIS has been in service since 2006; as such, it is approaching the end of its operational lifetime, with most components being obsolete. A second version of the Beam Interlock System, "BIS2", is currently under development and will replace the current system. BIS2 aims to be more flexible by supplying additional on-board diagnostic tools, while also improving the overall safety by adding more redundancy. Crucially, BIS2 increases the number of critical paths that can be interlocked by almost 50%, providing an important flexibility for future additional interlocking requests. BIS2 will come into operation for the LHC in run 4 (2027) and will remain in operation until the end of the planned lifetime of HL-LHC. In this paper, we will focus on the Beam Interlock Controller Manager board (CIBM), which is at the heart of BIS2. Since this module works closely with many other systems that are similar in design to those in BIS1, we will compare how BIS2 improves upon BIS1, and justify the reasons why these changes were made.