Situational awareness is the operator's live grasp of what the plant is doing and where it is heading - but that grasp does not appear from nowhere. It is built, or destroyed, by the graphics in front of the operator. This guide looks at situational awareness specifically as a design goal for HMI graphics: the concrete techniques - analog representations, embedded trends, deviation indicators - that a screen uses to support an operator's perception, comprehension, and projection.
HMI Situational Awareness in one line: HMI situational awareness is the practice of designing operator graphics specifically to build and protect the operator's real-time understanding of the process. Framed by Endsley's three levels - perception, comprehension, and projection - it uses concrete graphic techniques: analog indicators that convey a value's position at a glance for perception, context such as limits and normal ranges for comprehension, and embedded trends and deviation indicators that reveal direction for projection. The design goal is a screen that hands the operator awareness rather than raw data.
Situational awareness is commonly described using Endsley's model, and each of its three levels is a distinct thing a graphic must support. Level 1, perception, is simply taking in the relevant data - which means the graphic must present the right values clearly and make abnormal ones salient, so the operator perceives them without hunting. Level 2, comprehension, is understanding what the data means together - which means the graphic must supply context, showing a value against its limits and normal range and grouping related information, so the operator reads a situation rather than isolated numbers. Level 3, projection, is anticipating what happens next - which means the graphic must reveal direction and rate of change, not just present state.
Treating these three levels as explicit design targets is what separates a high-performance graphic from a merely decorated one. A screen that shows accurate numbers but buries them in visual noise fails at perception. A screen that shows a value cleanly but gives no sense of whether it is high, low, or normal fails at comprehension. A screen that shows the current value perfectly but nothing about its trajectory fails at projection - it leaves the operator reacting rather than anticipating. Good HMI design deliberately builds each level, using specific graphic elements chosen because they support one or more of them.
Several specific elements do the work of building awareness, each mapped to a level. The moving analog indicator serves perception and comprehension at once: by drawing a value on a scale with its limits marked, it lets the operator perceive the value and comprehend where it sits relative to normal, pre-attentively, without reading and interpreting a number. Reserving color for abnormal states serves perception directly, ensuring the eye lands on what matters. Grouping related values and showing them together serves comprehension, letting the operator read a developing situation rather than scattered readings.
Projection - the highest and most valuable level - is served by trend and deviation information placed on the face of the value. An embedded mini-trend beside a reading shows the recent trajectory, so the operator sees a value drifting toward a limit before it arrives, which is exactly the anticipation that defines Level 3. A deviation indicator showing how far a value has strayed from its setpoint signals a loop losing control before it produces an obvious upset. These direction-revealing elements are what let an operator act ahead of problems. The design principle is that a value should rarely appear as a bare number - it should carry the context and trajectory that turn data into awareness.
In oil and gas, situational awareness is hardest to maintain precisely because the process is spread across many remote sites that one operator must hold in mind at once. Graphic design is what makes that possible: an overview built from analog indicators lets the operator perceive the health of the whole field at a glance, embedded trends on that overview support projection across sites, and consistent conventions mean each site's detailed screen is comprehended the same way. The graphic techniques scale awareness from one unit to a whole field.
A cloud SCADA such as Merobix supports this by reading tags from many geographically separated sites over Modbus, DNP3, OPC UA, and MQTT and rendering them into browser graphics that can follow these situational-awareness principles from the start. Building those screens with analog indicators, embedded trends, and reserved color - rather than colorful bare-number displays - is what lets a single operator maintain genuine awareness across a wide operation. This graphic-design focus complements the broader control-room view of situational awareness: the concept explains why awareness matters, and the graphic techniques described here are how a screen actually delivers it.
They follow Endsley's model: perception (taking in the relevant data), comprehension (understanding what that data means together), and projection (anticipating what happens next). In HMI design each is a target - clear salient graphics for perception, context such as limits and grouping for comprehension, and trend and deviation information for projection - so the screen actively builds the operator's awareness rather than just displaying numbers.
Moving analog indicators support perception and comprehension by showing a value against its range and limits at a glance; reserving color for abnormal states directs the eye to what matters; grouping related values aids comprehension; and embedded trends and deviation indicators support projection by revealing direction and rate of change so the operator can anticipate problems. The unifying idea is that a value should carry context and trajectory, not appear as a bare number.
Situational awareness as a general concept describes the operator's understanding of the plant and why losing it causes incidents. This page focuses specifically on the graphic design that builds it - the concrete display elements and techniques a screen uses to support each level of awareness. One is the human-factors idea; the other is how HMI graphics are engineered to deliver it.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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