Functional block used in realizing cause and offect matrix in treating safety system

Abstract

A cause and effect function block, which can be easily integrated into a function block diagram programming environment in a process plant safety system to implement the cause and effect logic specified by a traditional cause and effect matrix, includes a set of cause inputs and a set of effect outputs. A multiplexer within the cause and effect function block receives each of the cause inputs and is coupled to one or more state machines, with a separate state machine existing for each effect output. The multiplexer decodes each of the cause inputs and, based on the cause inputs and previously identified cause and effect matrix logic, provides a trip signal to one or more of the state machines. Upon receiving a trip signal, a state machine forces an associated effect output into a tripped or safe state. If desired, the state machine may then use one or more other signals, such as signals from a user or from the process, to transition between a set of different states used to safely return the process plant back to the normal operating state from the tripped or safe state.

Description

technical field [0001] The present invention relates generally to a security system for use in a processing device, and in particular to a functional block implementing a causal matrix for controlling the operation of the security system used in the processing device. Background technique [0002] Similar to process control systems used in chemical, petroleum, or other processing, process control systems typically include one or more process controllers that communicate via analog, digital, or combined analog / digital buses or lines is coupled to at least one host or operator workstation, and one or more field devices. The field devices, which may be, for example, valves, valve positioners, switches and transmitters (eg, temperature, pressure and flow rate sensors) perform functions within the processing device such as opening or closing valves and measuring process parameters. The process controller receives signals indicative of process measurements made by the field devic...

AI Technical Summary

Problems solved by technology

Since safety logic transformed in this way can lead to highly complex programs, these programs can still be difficult and time-consuming to test and debug, and these programs can require extensive documentation

Furthermore, it is difficult to use such a program in a control routine using a function block programming strategy to perform a control function

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