Status of timing system and its upgrade for the PLS storage ring

The timing system for the Pohang Light Source (PLS) storage ring consists of a trigger synchronize module, a fine delay module, a repetition rate pulse generator module, and so on. All the timing modules are installed in the VXI crate and controlled by the 32 bit microprocessors with the host computer. Although the timing system has been operated without any serious problems since commissioning in 1994, there were some minor troubles, and the performances were not so excellent. Therefore, upgrade of the timing system is progressing with a synchronous universal counter and other commercial modules of NIM type for increasing of a reliability, easy maintenance, low timing jitters, and all types of beam filling pattern.