SVD DAQ System

The SVD DAQ system consists of a data manager, a run manager and an interlock. The data manager transfers data from the FADC output FIFOs to the central event builder and the run manager controls the DAQ hardware. The interlock monitors running conditions and sends signals to the run manager when an abnormal state is detected. Fig. shows a block diagram of the data acquisition and the monitoring system for SVD. The SVD back-end electronics system comprises a TTM system in a VME crate and four FADC VME systems. An FADC system consists of eight FADC modules and a SPARC VME module. The VME modules (TDM, TTMs and HALNYs) are controlled by a VME master module (i.e. a SPARC VME module) in each VME crate.

Figure: Block diagram of the SVD DAQ system.

The four FADC subsystems collect and transmit data to the event builder in parallel. SPARC VME boards resident in each of the four FADC crates carry out this task. The SPARC VME boards poll the status of each HALNY board in its crate and waits for a response indicating that a digitized event is ready to be read. HALNY data is transferred from the output FIFOs on a word-by-word basis. The SVD run manager controls DAQ VME modules (TDM, TTMs and HALNYs). It initiates or terminates trigger sequences, downloads firmware to the TTMs and Halnys, and issues resets at the beginning of each run and when requested by CDAQ. It also controls the run mode of the VA1 and CORE front-end electronics, via TTMs. Finally, it initiates recovery procedures upon request from the interlock. The SVD interlock system monitors running conditions of SVD. The data integrity is checked by the consistency of the event size and begin/end event markers. The condition of VA1s is monitored by checking the digital outputs from the hybrids and by tracking their power-supply currents. Temperatures of the hybrids, heat-sinks and end-rings, and water circulation are monitored to make sure that the cooling system is in working order. The beam abort signal from the radiation monitor described below is also fed into the interlock. When the system senses a fault condition on one of its inputs, it shuts down the power supplies for the front-end electronics and sends an abort signal to the run manager.