The ATLAS MDT Control System
S.Zimmermann (Freiburg) G.Bobbink, R.G.K.Hart* (NIKHEF)
The MUON spectrometer of ATLAS consists of four major parts by which the Muon-Drift-Tube chambers (MDT) are in terms of space and readout-channels the largest. The Detector Control System (DCS) of it can be separated into a CAN field-bus part (temperature readout, magnetic field readout and control of the front-end electronics (FE)) and a non-CAN field-bus part (gas, high- and low-voltage). This article covers only the first part (CAN). For this purpose each MDT-chamber is equipped with a so-called Muon-DCS-Module (MDM), containing a CAN-node. About 1200 chambers are connected divided over roughly 90 CAN-buses, monitored and controlled by a commercial SCADA system (PVSS) running on 10 PC's. The temperature and magnetic field sub-systems are mainly used for off-line analysis and their data is stored at regular intervals into a database. The FE sub-system is used, by means of JTAG, to set the thresholds and trip-levels of the DAQ readout electronics. The sub-systems are incorporated into the overall ATLAS Finite-State-Machine (FSM), which enables it to control it in a general and consistent way. Tools and applications were developed for maintenance and diagnostics.