Modelling the fast orbit feedback (FOFB) system for the upcoming PETRA IV storage ring is in progress. The single-input-single-output (SISO) simulations provide an abstract insight into the FOFB system's performance and stability. Nevertheless, to investigate the orbit correctability in general and at spatial locations of interest, i.e. insertion devices, the simulations are extended to include the lattice model. The multiple-input-multiple-output (MIMO) numerical simulations are being carried out in Python-based cpymad and Matlab-based Simulation Commissioning (SC) toolkit, and first results are presented.

At DESY, the technical design phase to upgrade the PETRA III storage ring towards the 4th-generation synchrotron light source PETRA IV is ongoing. This foresees a complete renewal of the machine including its existing timing and synchronisation system. The new timing and synchronisation system needs to deliver precise clocking, which will be implemented by an application-specific hardware design. Further on, it has to provide trigger signals and beam-synchronous information to the subsystems located across the facility. The main hardware for the timing system will be based on the MTCA.4 standard. This platform has been successfully implemented here at DESY / EuXFEL. Because of new specific requirements for PETRA IV, the successor hardware has to be adapted and upgraded to a new design. This paper describes the system design and the facility-wide distribution of precise clocks, trigger signals and timing system-related meta-information. We illustrate how the new MTCA.4-based AMC card (DAMC-X3TIMER) meets the requirements for PETRA IV. Insights into ongoing lab tests on components qualification and the status of the development will be presented.