Miyahara, F. Furukawa, K. Kaji, H. Kudo, T. Kusano, S. Saotome, H.S. Satoh, M. Sugimura, H. JACoW Publishing Geneva, Switzerland 978-3-95450-200-4 10.18429/JACoW-PCaPAC2018-THP19 English 207-209 THP19 linac timing injection gun laser Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-PCaPAC2018-THP19 http://jacow.org/pcapac2018/papers/thp19.pdf The KEK e⁺/e⁻ injector linac is operated in multiple modes that can be switched every 20 ms for e⁺/e⁻ beam injection to five different accelerator rings, SuperKEKB High Energy Ring (HER), Photon Factory (PF) ring, PF-AR, positron damping ring (DR) and SuperKEKB Low Energy Ring (LER). The MRF event system which consists of event generators (EVG) and event receivers (EVR) is used to distribute event codes that correspond to beam modes and data buffer. The EVR generates various trigger timing signals depending on the event code. The data buffer incudes some important parameters such as HER/PDR injection RF bucket, setting currents of pulsed quad/steering magnets that enables multiple beam injection. The event system uses the linac main clock (114.2 MHz) which synchronized to HER/LER, but due to PF and PF-AR rings are not synchronized to the linac, an additional synchronization system is employed for those rings. We will describe the timing and synchronization system to fulfill multiple injections to independent rings and report status of the system.