Glossary · Maintenance and diagnostics
Fault diagnosis
Also known as: Fault analysis
German: Fehlerdiagnose
In automation and maintenance, fault diagnosis is the process of determining the type, location and cause of a detected fault, using diagnostic data, tests and the knowledge of the system's structure.
- Maintenance
In one sentence
Fault diagnosis determines the type, location and cause of a detected fault using diagnostic data, tests and knowledge of the system.
Example
Using channel diagnostics from the I/O module and the wiring diagram, the technician diagnoses a short circuit in the cable to sensor B12.
How it applies
- Engineering: Good diagnosis depends on design: modules that report channel-level diagnostics, meaningful error codes and access to signal states make diagnosis faster.
- Maintenance: Technicians combine controller diagnostics, the Diagnostic buffer or Event log, measurements and drawings to narrow down the fault.
- Service: Remote diagnosis lets the machine builder support the operator without traveling, within the limits set by the plant's security rules.
- Documentation: Diagnostic procedures belong in the maintenance manual: which tool to use, which values to check and in which order. Structured cause/remedy tables and a consistent message catalog make the content reusable in HMIs and service portals.
Fault diagnosis vs. troubleshooting
Fault diagnosis is the analytical part: identifying the fault. Troubleshooting covers the whole practical sequence from symptom to restored function, including the repair and the functional check afterwards.