ADVANCED USES OF THE WORLDFIP FIELDBUS FOR DIVERSE COMMUNICATIONS APPLICATIONS WITHIN THE LHC POWER CONVERTER CONTROL SYSTEM
Q. King · 2005
The LHC power converter control system is based on an embedded computer designed at CERN called a Function Generator/Controller (FGC). Every one of the 1700 LHC power converters will include an FGC responsible for the control and monitoring of the converter’s state (on, off, standby, etc…) as well as the generation of the current reference and the regulation of the measured current. The operation of the LHC will require the coordination of all 1700 power converters, so synchronisation is fundamental. Given the large scale of the system, both in terms of the number of nodes and their geographical spread (27 km), it was decided to use a fieldbus for communications. It was found that by choosing the WorldFIP standard, which has a real-time behaviour, it was possible to support data communications and synchronisation over the same twisted pair cable. This paper describes how the underlying WorldFIP protocol has been adapted to support all the communications requirements of the FGC. These include: (i) a packeting layer for commands and responses, (ii) 50 Hz publication of power converter and circuit status, (iii) broadcast of UTC time and events (e.g. start ramp, end ramp), (iv) 50 Hz transmission of real-time reference values to support orbit, tune or chromaticity feedback, (v) broadcast of software updates, and (vi) support for remote