Inter-generational compatibility study of MRF event timing modules

Event timing systems are critical for the synchronization of beam diagnostics and accelerator control at KEK LINAC. Such systems have historically relied on VME-based modules since 2008, such as the MRF 230 series event generator and event receiver. However, with some VME modules approaching its market end-of-life, transitioning to modern platforms like MicroTCA is becoming imperative. This work addresses the challenges of such a migration by focusing on a phased upgrade approach, where new MicroTCA-based MRF 300-series timing modules will coexist with and eventually replace the legacy VME timing modules. A primary concern during this transition is ensuring the functional compatibility between the old and new generations. This paper presents a comprehensive evaluation of critical timing function across coexisting VME and MicroTCA systems. Core compatibility aspects evaluated include event code transmission and reception accuracy, timing precision and jitter, trigger output characteristics, event rate handling, sequencer operation, distributed bus signal integrity, and timestamping consistency. The findings aim to provide a quantitative assessment of compatibility, identify potential limitations, and offer practical insights for other facilities planning a similar upgrade of their MRF event timing systems, thereby minimizing risk during the accelerator operation.