Plans at CERN for electronics and communication in the Distributed I/O Tier

Controls and data acquisition in accelerators often involve some kind of computing platform (VME, PICMG 1.3, MTCA.4…) connected to Distributed I/O Tier electronics using a fieldbus or another kind of serial link. At CERN, we have started a project to rationalize this tier, providing a modular centrally-supported platform which allows equipment groups to focus on solving their particular problems while benefiting from a set of well-debugged building blocks. The paper describes the strategy, based on 3U Euro crates with a generic FPGA-based board featuring space for FMC mezzanines. Different mezzanines allow communication using different protocols. There are two variants of the electronics, to deploy in environments with and without radiation tolerance requirements. The plans we present are the result of extensive discussion at CERN among all stakeholders. We present them here with the aim of gathering further feedback and potential interest for inter-lab collaborations.