A position feedback system using LON for the active supporting table

Accelerator Test Facility (ATF) consists of 1.54 GeV electron linac and a low emittance damping-ring to test and verify many crucial elements of future linear collider. Thirty-six active supporting tables are installed in the arc position of the ring. Each table supports magnet-complex. Three jacks support the table. Each table has 3 linear sensors (LVDT). A leveling sensor of half-filled with water (LSHF) for every active supporting table is set just in side of the table. Here, each component of the system as well as feedback system using LONTALK, a protocol used in the control system of local operating network (LON) was discussed in detail and the good performance of the closed system was shown. The development of the feedback system was very easy by using LON and the feedback system works very well if it keeps the vertical redundancy of the active supporting table at the range of ±3 μm. As a result of the feedback, the active supporting table could be held within a required vertical tolerance, 20 μm. (M.N.)