Perhaps, when you read these questions, you will wonder for a moment whether they are really all the same. And some experts are suddenly no longer sure either. We won't keep you in suspense any longer ...
In short: All expressions describe the requirements of a product, for example software, from the user's point of view. They are usually created when a new system is purchased or an existing system is modified with the following contents:
In this article we restrict ourselves to programmable logic controllers, so-called PLCs.
The four guiding questions mentioned above should be asked and answered by everyone when creating a user requirement or even a specification.
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URS A URS is written by the group of people who will use the software or computer system. The requirements are described and not the finished solution. The different requirements must not contradict each other. The user requirements can be described in tabular form or in continuous text. The advantage of the tabular form is the clarity and the assignment of a number to a user requirement. The traceability of user requirements is thus given. The disadvantage of the tabular form is the short description of the user requirements. |
Example: I would like a handwriting instrument with document-proof ink. The ink must be blue and the handwriting implement must not weigh more than 100g, have a total length of max. 20cm and be approx. 15mm thick in diameter.
Not: I want a biro of the brand XYZ1 that writes blue. That would already be the solution.
The German knowledge and learning portal for equipment qualification, GMP:KnowHow Anlagenqualifizierung, uses an example to show what a user requirement for a PLC might look like. Based on guiding questions, the development of a PLC URS is explained. In this article, we give you an insight into the structure and excerpts from the more than 50 guiding questions.
The following areas and topics form the structure of a URS:
First you start with a short project description. The URS is normally sent to one or more potential suppliers. This way they know what it is about and can propose a suitable solution.
Possible guiding questions for a project description could be:
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Possible guiding questions are:
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Human Machine Interface (HMI) requirements are the ease of use of a computer system/software.
Possible guiding questions are:
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Possible guiding questions are:
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Possible guiding questions and documents to be produced are:
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Possible guiding questions are:
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Possible guiding questions are:
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Based on such guiding questions, detailed user requirements can be created, which significantly facilitates the creation of follow-up documents such as the software quality plan, functional specification, test plan and report for the PLC.
The article is an excerpt from the German kowledge portal for equipment and systems qualification GMP:KnowHow Anlagenqualifizierung.
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