Plant Hazard Analysis and Safety Instrumentation Systems

4.6. ESD Configuration and HMI

Typical configuration for an ESD system is shown in Fig. VIII/4.6-1. All field inputs from process variables and outputs to various actuators' MCC shall be connected to the ESD system with the help of an I/O bus. Depending on applicability there could be redundancies in various systems and the communication bus, as shown in Fig. VIII/4.6-1. Redundancies are shown with shadows. In the case of other systems where there are multiple systems, these are also shown with the help of shadows. Some systems (say an alarm system) may have an RS 485/422 link. In this configuration an attempt is made to highlight that the system is an independent system but can have an interface with other systems as well. At the top layer, Ethernet ...