Développement d'un système visualisation des taux du HLT dans le système de supervision PVSS du LHCb

At CERN, the Online group of the LHCb team is in charge of data acquisition and of the control system. Intersting data are selected by different triggers. The HLT, for High Level Trigger, is a distributed system which should reduce the rate of selected events from 1 MHz to 2 kHz. In order to monitor the HLT's work, some rates are published at different levels of the HLT using the DIM system. The purpose of the presented work is to provide a way to display and archive this rates in PVSS. This work involves a server converting rates published by the HLT into a format that PVSS can handle. This server, called RateService, is written in C++. A client, called RateCtrl, developed as a PVSS project, is in charge of displaying and archiving this converted rates using standard components developped by CERN. Communication between the server and the client is also provided by DIM. The server is now working and has been commissioned in the pit. The client has been installed and tested. It is available as an LHCb FrameWork component.