PESCA instrument control system

Abstract. The description of the PESCA instrument controlsystem is presented. The PESCA instrument has beendesigned and built with the purpose of studying the SolarEnergetic Particles and the Anomalous Cosmic Rays fromhelium to iron in the energy range 1.5-50 MeV/uma andwill be part of the Russian PHOTON satellite payload. Theinstrument comprises two different blocks: the PESCAInstrument Amplification and Shaping Electronics(PIASE), for the amplification and analog to digitalconversion, and the PESCA Instrument Control andAcquisition System (PICAS), for the control of the wholeinstrument. A system has been mounted to control and testthe PESCA instrument. It allows the complete control overthe instrument, verification and validation of the PESCAinstrument (unit tests, integration tests and system tests) andPESCA calibration, from a single PC under Linux operatingsystem.1 IntroductionThe control system that has been mounted in the laboratoryis depicted in figure 1. It is composed of the PESCAinstrument, an On Board Data Handling (OBDH) Emulatorand, finally, a PC computer with the Electrical GroundSupport Equipment (EGSE) software.The PESCA instrument (del Peral et al., 1995; del Peralet al., 1997; Prieto et al., 1999) is composed of a telescope,made up of four silicon ion implanted detectors, whichregister the particle crossing through the detectors, thePIASE for signal amplification and analog to digitalconversion, and the PICAS, for the control of the wholeinstrument. PICAS is composed of a Data Processing Unitbased on the MAS281 microprocessor and a set ofinterfaces with the rest of the instrument and the satellite.PICAS admits telecommands sent from ground for dataacquisition and control parameter setting. Thecommunication between ground and PICAS is performedthrough the OBDH.The OBDH emulator acts as the satellite on boardcomputer and it fulfills the OBDH ESA standard. Thecommunication between OBDH emulator and EGSE isperformed through two serial RS232 ports, one fortelecommands and one for telemetry.In the other hand, the EGSE software, developed forLinux operating system, allows the complete control overthe instrument, being the end point of the system. Itbasically allows the telecommand sending and datareception, making possible the verification, validation andcalibration of the PESCA instrument.