Requirements for the Mediterranean LGV

Under the Mediterranean LGV project, preliminaiy studies have shown the benefits of integrating interlocking and signaling functions into a single safety computer in order to significantly rednce the nnmber of safety relays necessary to set up a signaling terminal. 

To meet the needs of the Mediterranean LGV, Ansaldo STS France designed and implemented the CSD. The CSD is characterized by two major changes compared to 

The principle of the safety computer (outside availability) of the Mediterranean LGV is composed of five blocks supported by standard microprocessor cards, fir fact, the only safety constraint weighing on CSD equipment is the implementation of two independent clocks the safety of the computer is entirely ensnred by the software. 

The CKD dynamic controller has been removed and, strictly speaking, is no longer part of the computer. The coupler formats the data (either through a series connection, or through a transmission network) and supplies them to the physical input/output device (DESP dispositif d entree sortie physique). The DESP does not form part of the CSD. 

The DESP ensures the physical input and output. In the Mediterranean LGV application, the DESP was implemented in an input/output basket with a coded uniprocessor computer, a CKD and ouQ)ut cards (CSS cartes de sorties), and safety input cards (CES cartes d entree de securite). In recent applications (Spain LGV), the DESP is implemented using MTOR cards (processor card with encoded COLDFIRE and CKD integration), handling 48 inputs/outputs on a single card. 

---