White-Rabbit Based Revolution Frequency Program for the Longitudinal Beam Control of the CERN PS

The measured bending field of the CERN Proton Synchrotron (PS) is received in real-time by the longitudinal beam control system and converted into the revolution frequency used as set-point for beam phase and radial loops. With the renovation of the bending field measurement system the transmission technique is changed from a differential sequence of pulses, the so-called B-train, to a stream of Ethernet frames based on the White Rabbit protocol. The packets contain field, its derivative and auxiliary information. A new frequency program for the conversion of the bending field into the revolution frequency, depending also on parameters like radius of the accelerator and the particle type, has been developed. Instead of storing large conversion tables from field to frequency for fixed parameters, the frequencies are directly calculated in programmable logic (FPGA). In order to reduce development time and keep flexibility, the conversion is processed in real-time in the FPGA using Xilinx floating-point primitives mapped by a higher level tool Simulink System Generator. Commissioning with beam of the new frequency program in the PS is progressing.