Fault Modeling

Definitions

Fault is a physical failure mechanism.
Fault Effect is the logical effect of a fault on a system.
Error is the state of a system containing a fault.

Fault Modeling Goals

Model defects in the system at the highest level of abstraction possible:

• Reduces the number of individual defects that have to be considered
• Reduces the complexity of the device description that must be used in test generation and analysis
• Allows test generation and analysis to be done as early in the design process as possible

Model as high a percentage as possible of the actual defects that can occur.

Possible failures are grouped together regarding their logical effect into Logical Fault Models as the basis for Test Generation.

Faults Classification

Cause

• Specification Mistakes
• Implementation Mistakes
• External Disturbances
• Component Defects

Extent

• Local
• Global

Duration

• Permanent
• Transient
• Intermittent
• Delay

Nature

• Software
• Hardware
• analog
• digital