The DABC Framework Interface to Readout Hardware

The Data Acquisition Backbone Core (DABC) is a new GSI software framework to run a data acquisition with distributed event building on high performance Linux clusters. Experiment specific front-end electronics is to be integrated to the software by means of hardware interface plug-ins like Device and Transport classes. DABC offers elaborate mechanisms for multiprocessing, buffer management, and dataflow throttling. These are transparently available for all implemented plug-ins. Device plug-ins can link a DABC node to remote readout hardware via network connections like Ethernet. Other Device plug-ins can communicate on the Linux device driver level with custom boards directly inserted at the node. Besides delivering the data input, a DABC Device can also provide control access to the connected hardware. This functionality can be used for setting up, or monitoring the front-ends from the application via DABC parameters and commands. An implementation example is a multipurpose PCI Express Optical Receiver (PEXOR) board developed at GSI. This board features an FPGA and 4 optical links and may be used for various front-ends, depending on the FPGA programming. A kernel driver and the DABC Device plug-in for this board have been developed and tested. They are described here with some performance bench-mark results. As another example, DABC is applied for data taking during test beam times of the Compressed Baryonic Matter (CBM) experiment from 2008 to 2010. Here the front-end readout controller boards (ROC) were integrated to the DABC hardware interface, both for a UDP based Ethernet protocol, and for optical connections to a custom PCIe board.