Requirements Phase

 

Requirements Phase

 

The Requirements Phase uses the outputs of the System Lifecycle Process to develop the High Level Requirements. These High Level Requirements include functional, performance, interface, and safety-related requirements, ref. DO-254 Section 5.1.

 

The inputs to the Requirements Phase are as follows:

 

• System Requirements Data (SRD) allocated to hardware
• Hardware Interfaces and System Architecture
• Hardware Development Plan
• Hardware Requirements, Design, and Implementation Standards (HRDIS)

 

The outputs to the Requirements Phase are as follows:

 

• Hardware Requirements Document (HRD)
• Hardware Signal Dictionary (HSD)

 

Hardware Requirements Document (HRD)

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The primary purpose of the Hardware Requirements document is to give a detailed description of the hardware at a component level. This document covers the Hardware Specifications for the Hardware Item. The functional behavior of the Hardware Item is broken down according to each sub component’s functionality. Partitioning of the functionality will assist in determining operational capabilities and resources. The HRD is very specific in that an HRD may be created to describe the functionality of each sub-component of the hardware item.

 

Hardware Signal Dictionary (HSD)

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The Hardware Signal Dictionary is an output of the requirements phase and is usually in the form of an excel spreadsheet. This document will lists all of the input and output signals for the hardware component as listed in the requirements document. This document can sometimes be referred to as an Interface Control Document. Requirements will be written for each function that the hardware item performs and each output it generates. The signal dictionary lists the signals, their type, operational min and max ranges, units, tolerances, etc.