Evaluation of software

Modern systems for critical applications almost always include the software as a part of the critical function.  As opposed to hardware, no new errors are introduced into the software after the system has been commissioned:  instead, it is during the development stage that errors may be introduced.  It is therefore important that the software development process should in itself be well-proven, and that verification and validation should be properly performed. 

In the case of systems of which the results would be catastrophic in the event of loss of a function, it is normally a requirement that the software should be evaluated by an independent third party. 

Evaluation of software includes checking that the software architecture is properly structured and modular, that a coding standard has been employed, and that probability checks have been applied to the indata for functions.  In addition, it is common to perform data flow analyses and control flow analyses which can find, for example, inactive code, code which is never accessed, or variables that are written but never read. 

Other reviews include more hardware-related aspects such as running regular memory tests and monitoring the program execution. 

SP has many years' experience of evaluation of safety-critical software, and can provide the following services in these fields: 

Evaluation of software in accordance with: 

• IEC 61508-03
• RTCA DO-178B

Evaluation of the safety of software with respect to: 

• Data flows 
• Program execution

Quality control of software in connection with:  

• Version management
• Documentation
• Development process

Evaluation of software constructed from models and with automatic code generation

• Matlab, Simulink, TargetLink
• Rhapsody
• SCADE

Evaluation of software in measuring instruments under the Measuring Instruments Directive

• Weighing Instruments
• Energy meters
• Taximeters 

These methods are by no means exhaustive, but should be seen as a sample of what SP can offer.