Glossary · HMI, SCADA and operations
Warning (HMI message)
Also known as: Warning message (HMI), Pre-alarm
German: Warnung
In HMI and SCADA systems, a warning is a message class indicating an abnormal but not yet critical condition, such as a value approaching a limit or a maintenance interval running out, which requires attention but usually doesn't stop the machine.
- HMI and SCADA
In one sentence
An HMI warning signals an abnormal but not yet critical condition that needs attention but usually doesn't stop the machine.
Example
The HMI shows the warning "Filter differential pressure high – replace filter at next stop" while the machine keeps running.
Explained in context
Context cards connect this term with others to answer one question. Also in British English and German.
How it applies
- Engineering: Warnings typically precede alarms or faults: a pre-limit before a trip, a wear indicator, a low consumable level. Decide per warning whether acknowledgment is required and how it is displayed.
- Operation: If warnings are ignored because they are too frequent or unclear, they lose their value. Each warning should say what to do.
- Documentation: Write warning texts with cause and action, and list them in the maintenance or operating manual. Keep the HMI meaning of "warning" separate from safety warnings in the instructions, which follow their own structure with signal words.
HMI warning vs. safety warning message
An HMI warning is a process or machine status message. A safety Warning message in the instructions (for example with the signal word WARNING according to ANSI Z535 or ISO 3864-2 conventions) informs about a hazard, its consequences and how to avoid it. Using the same word for both is common; documents and terminology databases should distinguish them.