Parallel read-out extension of the VME DAQ system

The VME bus is a legacy DAQ front-end system in nuclear physics experiments. Since a read-out controller takes data from VME ADC/TDC modules in order, the read-out time depends on the size of data. When the number of ADC/TDC modules becomes large, the DAQ dead-time will also be large. To avoid this sort of performance limitations of the legacy system, some newly developed front-end systems directly output data to Ethernet. In RIKEN, we have developed the MOCO board to speed up the VME system. MOCO is a tiny VME controller which can be attached to the VME module without the VME bus. Since functions of VME controller is implemented on FPGA, the data read-out speed is very fast. However, there are some problems on stability, usability an electrical safety. Here, we developed a new backplane and a master read-out controller for MOCO to build more robust system. MOCO reads data from each VME module, and data is forwarded to the master controller through the new backplane. The master controller combines data from multiple MOCOs and send data to Ethernet. The new backplane can be installed on a standard VME power supply and chassis. In this contribution, details of the system and some performance measurements will be shown.