Identification is only the start
A tag helps engineers and operators refer to the same function. The HMI must also present the value, engineering units, quality, mode, alarm condition, and access to detail in a consistent hierarchy.
Do not shrink a complete instrument bubble until its letters become unreadable. At overview scale, a value and concise label may work better; preserve richer identification in the detail view.
Design the readout
- 01
Label
Use the approved tag or a clear service label according to the display level.
- 02
Value
Align precision with the instrument and operating decision, not available decimal places.
- 03
Quality
Make stale, bad, substituted, or uncertain data visible without relying on color alone.
- 04
Action
Provide predictable navigation to faceplates, trends, alarms, or diagnostics.
Sources and boundaries
KonnectSymbols is independently developed and is not endorsed by ISA, IEC, or ISO. These educational notes do not reproduce or replace current standards, project specifications, regulations, or an approved project legend.
- ANSI/ISA-5.1-2024 Instrumentation Symbols and IdentificationInternational Society of Automation. Official publisher page for the current ISA-5.1 edition and related technical reports.
- ISA-101 Human-Machine InterfacesInternational Society of Automation. Official publisher page for the ISA-101 series. The full standard requires publisher access.