Design and implementation of data transmission of fast orbit feedback system for HEPS

High Energy Photon Source (HEPS), as a 4^th generation synchrotron radiation light source, has stringent requirement for beam orbit stability: the orbit fluctuations should be below 10% of the beam RMS sizes in both horizontal and vertical directions with a bandwidth around 500 Hz. Overall, the latency of the Fast Orbit FeedBack (FOFB) system is the key factor to achieve the requirement. Data transmission of the beam positions from the beam position monitor (BPM) electronics to all of the FOFB sub-stations is the key to achieve very low latency, as which contributes the largest part of the total FOFB system latency. Preliminary test results of prototype showed that the total latency of data transmission is less than 10 μs with no bit errors during data transmission, satisfying the requirements on the FOFB system of HEPS.