Outcome of the Commissioning of the Readout and Actuation Channels for the Cryogenics of the LHC

The instrumentation readout is performed through two types of field-busses: Profibus® that is not meant to operate on radioactive environment, and therefore is confined to zones outside the accelerator tunnel. It is used for the valve signals and some special heaters. For each sector, remote I/O modules, located in four underground “protected areas”, are connected through optic fiber to the two PLC (one for the arc, one for the Long Straight Sections, LSS) that are located on the surface. WorldFIP®, that carries the data from the thermometers, pressure sensors, level sensors and heaters. For each sector, 80 stand-alone crates, holding the radiation-tolerant electronic modules, are evenly distributed along the arc inside the LHC tunnel. Other 20 crates per sector are in protected areas, and are dedicated to the instrumentation of the LSS. On each sector, eight Front End Controllers (FEC) PCs running Linux, are used as a gateway to interface data from the WorldFIP® I/O modules to the Siemens Profibus® PLC. Two supervision systems (SCADA) operate in parallel: the CRYO used for the LHC cryogenic operation, and the CIET used for the access to the full data of the WorldFIP® instrumentation channels.