Distributed embedded and re-configurable control and monitoring system for large-scale detectors

Controlling and monitoring the complex front-end electronics of large-scale detector systems like the TPC, TRD, PHOS and the HLT systems in the ALICE experiment at the LHC/CERN requires a distributed, fault-tolerant control system for the front-end electr onics containing up to 2000 nodes. Each node contains re-configurable hardware combined with an embedded micro-controller running LINUX. The complexity and the real-time requirements demand a fast, autonomous and distributed processing scheme close to the sensors. The readout electronics is controlled by up to 2000 embedded LINUX systems combined on the same chip with an FPGA. Both a hardware interface to the detector/sensor and an embedded controller are implemented in the FPGA. A small LINUX system run ning on the synthesized or hardwired CPU controls the hardware, collects data and communicates via ethernet, TCP/IP and high-level protocols (e.g. DIM) with the central control and monitoring system (SCADA). Time-critical tasks are performed by control en gines, either synthesized in the FPGA or executed in the processor. Special care has to be taken in order to make the system fault-tolerant due to the radiation environment and non-accessibility of the devices.