Technical architecture of the system

It should be noted that the MEI modules are duplicated through hot redundancy . This provision was adopted to simplify to a minimum (therefore to render more reliable) the management structure of the commutation. Also for this reason  

The PCD is a remote command and control system, the availability of communications is guaranteed by the existence of a communication ring (direct link and link loopback). 

All safety equipment (MEI) located on different command and control sites are supervised from a remote command and control center. This requires the presence of a single operating agent. 

The flow of information between the remote command and control station and the equipment on site is, on one hand, a return flow of the overall condition of the field equipment (field control). This information constitutes the field vision of the operator and, on the other hand, a command flow (operator dialogs) in order to call upon the functionalities of the system. The display function is performed with a SIL 3 (alternating graphics plan, refresh time of less than 6 seconds, etc.). 

It consists of standard equipment (IBM/PC). It is a system doubled up with a cold reserve for availability reasons. 

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