Functional Requirement Specifications (FRS) are prepared for each critical utility or piece of equipment prior to the manufacturing stage. The specification provides a functional list of the requirements for the planned system based on the User Requirement Specification (URS) that is created prior to the FRS. The FRS will take the user requirements and specify how they should be manufactured in order to respect the requirements. The document is provided to the supplier in order to ensure that all expected functional requirements, of the end user, for the utility or piece of equipment have been specified and supplied prior to the manufacturing stage. These specifications will form the basis for the Detailed Design Specifications and the Hardware and Software Specifications that details the design of the utility or piece of equipment.

Why produce an FRS?

Functional Requirements Specifications are required to protect both the end user and the manufacturer. All Requirements of the end user will be specified in the FRS prior to the manufacturing of the utility or piece of equipment. This enables the manufacturer to produce the product to the end user’s expectations. The manufacturer has the opportunity to review the FRS and incorporate the requirements in their system or offer alternatives to meet the requirement. Some requirements may not be possible to supply and therefore will be addressed prior to the manufacturing stage eliminating possible problems before they occur. The Functional Requirements Specification document may evolve with the project and is provided with a Revision History section in order to document any changes that occur throughout the project stages. The final version of the FRS will be a controlled document that can be referenced should any questions arise regarding the final product. The manufacturer must ensure that all aspects of the FRS have been understood and that all requirements can be fulfilled, or alternatives offered, in order to meet the end user’s expectations.

What does an FRS contain?

The Functional Requirements Specifications include (but are not limited to) the following common sections:

Identification of Writer, Approvers:
Provides documented evidence on the personnel involved in preparing and approving the document.

Revision History:
A revision history is maintained to record any changes to the document and the date they occurred.

Introduction:
Defines the purpose and scope of the Functional Requirement Specification with respect to the design of the utility or piece of equipment.

Overview:
Gives a background and objective of the utility or piece of equipment that is being considered with an overview of its functions.

Operational Requirements:
Will list the requirements for the function of the system which include, but are not necessarily limited to, Sequence of Operation, Cycle of Operation, and Machine Performance.

Control System Requirements:
Will list the requirements for the control system which include, but are not necessarily limited to, Functions, Safety, User Interfaces, Electronic Records and Signatures, Security, Alarms, and Utilities.

Hardware and Software Requirements:
Will list the specific requirements for the control system which include, but are not necessarily limited to, Interferences, Environment, Hardware, Operating System, and Application Software.

Glossary:
Definition of all the terms that have been referenced in the document.