HMI symbols & SCADA symbol libraries

HMI and SCADA symbols are the graphic objects an operator actually looks at — the motors, pumps, valves, tanks and instruments on a control screen. The thing that makes them different from a drawing symbol: they are live. Each one is bound to a PLC tag and changes state in real time. This guide explains what they are, how they differ from static P&ID symbols, the calm ISA-101 color rule behind them, and how to get a vendor-neutral symbol library as PNG/SVG.

What is an HMI symbol?

An HMI symbol (Human-Machine Interface symbol) is the on-screen representation of a piece of plant — a pump, a conveyor, an on/off valve, a level instrument. On an operator display it does two jobs at once: it shows where the equipment sits in the process, and it shows what state the equipment is in right now.

That second job is the key difference from a static graphic. An HMI symbol is typically a multi-state object: the runtime swaps its appearance — color, an alarm badge, a blink, a direction arrow — based on the value of one or more PLC tags. A motor symbol is gray when stopped, green when running, amber when it has no feedback, and carries a red badge when it is in a priority-1 alarm. Same graphic, different states.

HMI symbols vs SCADA symbols

The terms are used almost interchangeably, and the same library serves both. The distinction is one of scope, not graphics:

• HMI — the local interface to a single machine or cell, usually a panel-mounted touchscreen close to the equipment (Weintek, Siemens Comfort Panel, Rockwell PanelView).
• SCADA — Supervisory Control and Data Acquisition: a higher-level system that monitors and controls many machines, lines or even remote sites from a control room (Ignition, WinCC, Citect, AVEVA System Platform).

Both render the same kind of dynamic, tag-driven objects, so a SCADA symbol library and an HMI symbol library can be one and the same set of files. What matters is that the symbols are consistent, legible at a glance, and standards-based — which is where ISA-101 and ISA-5.1 come in.

How HMI symbols differ from static P&ID symbols

A P&ID symbol is documentation. It tells an engineer what equipment exists, how it is piped, and what its tag is — but it never changes. An HMI symbol takes that same shape vocabulary and makes it dynamic:

The clearest example is a motor. On a P&ID it is a single circle marked M. On an HMI it needs a defined set of states the operator can read instantly. We cover the full set — stopped, starting, running, no feedback, manual, disabled, P1/P2 alarm and fault — in the 9 motor states every HMI should show, including how each maps to a PLC tag and a multi-state lamp.

The calm ISA-101 color philosophy

The single most important rule for an HMI symbol library is restraint with color. ISA-101 — the standard for HMI design — calls for a low-saturation, mostly-gray base screen so that the few things that are colored genuinely grab attention. Color is information, not decoration.

In practice that means symbols are drawn in neutral grays on the canonical #C8C8C8 HMI background, and color is reserved for status and alarms:

• Running / start — green.
• Stopped — gray.
• No feedback / caution — yellow.
• Manual — blue.
• Alarm priorities — red (P1), orange (P2), yellow (P3), blue (P4).

A screen full of colorful 3D pipes and gradients does the opposite of what an operator needs: when everything is loud, nothing stands out. The calm palette is why a well-built HMI symbol library looks deliberately understated. We go deeper — including color-blindness considerations and anti-patterns — in the calm HMI color palette guide.

Vendor-neutral export: one library, every platform

The HMI and SCADA market is fragmented across many editors, and most of them import standard image assets rather than a proprietary symbol format. The portable approach is to keep symbols as plain, transparent images and let each tool use them as multi-state graphics:

• Transparent PNG at 256×128 or 512×256 — drops straight into raster-based editors. In Weintek EasyBuilder Pro, for example, you import the PNGs into the Picture Library and map each state of a Multi-state Lamp to a PLC value.
• Scalable SVG — for vector platforms such as Ignition, Siemens WinCC and AVEVA, where graphics can scale without blurring.

The same exported set works across Weintek EasyBuilder Pro, Siemens WinCC, Rockwell FactoryTalk View, Inductive Automation Ignition, AVEVA (Citect / System Platform) and any other tool that accepts PNG or SVG. Because the assets are standards-based and vendor-neutral, you are not locked into one HMI ecosystem — the library moves with you from project to project.

How to get HMI & SCADA symbols

Two practical options, both producing vendor-neutral PNG + SVG:

1. Browse the catalog — a ready-made library of ISA-101 / ISA-5.1 symbols. Filter by category, tweak the palette and font live, and export individual files or a .zip pack.
2. Build your own — compose a symbol from ISA shape primitives and catalog parts in the free online Symbol Builder, recolor it to the ISA-101 palette, and export.

Start from the most common equipment families:

Frequently asked questions

Keep reading

• P&ID symbols explained — the full guide to every symbol family.
• P&ID valve symbols — bodies, actuators, fail-safe positions and tags.
• ISA-101 HMI design standard — calm color, alarm priorities, hierarchy.
• The 9 motor states every HMI should show — multi-state mapping in practice.
• Build your own symbols — free online editor.