Abstract This paper presents development of a new tag supply system for the data-acquisition (DAQ) system for SACLA user experiments. The X-ray Free-Electron Laser facility in SPring-8, SACLA, has delivered X-ray laser beams to users since March 2012. For the user experiments at SACLA, a dedicated DAQ system has been developed. The DAQ system is currently capable to operate with maximum twelve sensors of multiport charge-coupled device (MPCCD) for X-ray detection. The data of twelve sensors are read out with individual readout modules. We implement a new tag supply system to ensure the reconstruction of the diffraction image of the user experiments. The tag data are used to synchronize the data obtained by SACLA user experiments. One master server receives a signal given by accelerator and the delivery of the tag data follows to five experimental halls at SACLA and some of monitors at SACLA accelerator. We employ dedicated communication lines to deliver the tag data. The longest distance to deliver the tag data is about one kilometre. The new tag supply system has been operating stably since April, 2014
