Control system for Fermilab´s Low Temperature Upgrade

Fermilab recently upgraded the Tevatron cryogenic systems to allow for lower temperature operation. This Lower Temperature Upgrade grew out of a desire to increase the colliding beam physics energy from 900 GeV to 1000 GeV. A key element in achieving this goal is the new cryogenic control system designed at Fermilab and installed in 24 satellite refrigerators and 8 compressor buildings. The cryogenic improvements and addition of hardware like cold compressors exceeded the capability of the original distributed controls package. The new distributed controls package uses a Multibus II platform and Intel´s 80386 microprocessor. Token Ring is used as the link to the systems 6 primary crate locations with Arcnet used as the connection to the systems numerous I/O crates. I/O capabilities are double the capabilities of the original system. Software has also been upgraded with the introduction of more flexible control loop strategies and finite state machines used for automatic sequential control, like quench recovery or cold compressor pump down