AbstractThe Tore Supra Cryoplant is a vital and integral part of the experiment. It operates fully automatically and has been built for maximum specific operation for a tokamak. It includes over ten operating modes in order to save energy outside of plasmas operations. The present control system ‘Architecture 7’ is based on distributed Intel 8086 microprocessors. It includes over 1300 digital and 950 analogue input/output (I/O) cards. It has given excellent service for 10 years but difficulties of faultfinding, replacement of components and ageing circuit boards have degraded now the reliability of the cryosystem. Consequences of failures, faults and malfunctions might vary between some experimental hours lost to damage of some plant components. Cost maintenance and growing difficulties dictated an upgrade.