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The cryogenic plant built for the HERA accelerator at DESY in Hamburg (Germany) is now in operation for more than two decades. The commercial process control system for the cryogenic plant is in operation for the same time period. Ever since the operator stations, the control network and the CPU boards in the process controllers went through several upgrade stages. Only the centralized Input/Output system was kept unchanged. Many components have been running beyond the expected lifetime. The control system for one at the three parts of the cryogenic plant has been replaced recently by a distributed I/O system. The I/O nodes are connected to several Profibus-DP field busses. Profibus provides the infrastructure to attach intelligent sensors and actuators directly to the process controllers which run the open source process control software EPICS. This paper describes the modification process on all levels from cabling through I/O configuration, the process control software up to the operator displays. [ABSTRACT FROM AUTHOR]

A large aperture superconducting solenoid-magnet with fields up to 5.25 Tesla is being set up as high field test facility at DESY. It is used to measure prototype time projection chambers foreseen as detectors for a future high energy physics collider experiment. The new cryogenic supply of this magnet within the existing HERA cryogenic helium system is described. The cryogenic control, operation and results are outlined. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]