Test and Evaluation Station (TESt) - A Control System for the ALICE-HMPID Liquid Distribution Prototype

The sub-detectors and systems in the ALICE experiment [1] are of various types. However, during physics runs, all devices necessary for the operation of the detector must be accessible and controllable through a common computer interface. Throughout all other periods each sub-detector requires maintenance, upgrading or test operation. To this end, an access independant of other sub-detectors must be guaranteed. These basic requirements impose a fair number of constraints on the architecture and components of the Detector Control System (DCS). <P> The purpose of the TESt project consisted in the construction of a stand alone unit for a specific sub-system of an ALICE detector in order to gain first experience with commercial products for detector control. Although the control system includes only a small number of devices and is designed for a particular application, it covers nevertheless all layers of a complete system and can be extended or used in different applications. <P> The control system prototype has been implemented for the Perfluorohexane (C<SUB>6</SUB>F<SUB>14</SUB>) liquid distribution of the ALICE-HMPID (High-Momentum Particle IDentification)[5]. The application has been developed exclusively with components off the shelf: National Instruments BridgeVIEW [6] supervision software, SIEMENS PLC S7-300 [7] and the programming tool STEP 7. The OPC standard (OLE for Process Control) [8] was used for the communication between BridgeVIEW and the PLC.