Save Space in Control Panels with Dual-Status LED Indicators

Status indicators are a critical element of many control panels. They are especially important in equipment monitoring and process control, where operators need immediate visual confirmation of changing conditions. However, control panels often have tightly limited space, making it difficult to incorporate indicators that are easy to read under all operating conditions.

This article describes the challenges faced by designers of control panels. It then introduces dichroic LED indicators from APEM and shows how their ability to deliver two clear visual states from a single device can enhance visibility while conserving panel space.

The challenges of clear control panel design

While operators should be thoroughly trained before using industrial equipment, intuitive control panels support fast learning to speed the process and maximize productivity. Also, industrial operators are expected to use a wide range of equipment, so it is helpful to design control panels that offer some level of familiarity. Commonly used layouts, labeling terminology, and indicator colors ease the adoption of new equipment and minimize the chance of operator confusion. This design technique can be seen in car dashboards, where widely adopted indicators allow drivers to operate unfamiliar vehicles without studying the user manual.

Panel size and complexity also affect usability. Large panels allow designers to include numerous indicators or dedicate more visual space to important ones. Good design requires balancing these considerations to ensure that critical information is not missed and, at the same time, operators are not overwhelmed by excess information. Displays can be useful for consolidating information, but they can also make it difficult to see important notifications. Dedicated indicators help operators quickly identify important status changes to support safety and efficiency.

Control panel designers must also account for operating and environmental conditions that hinder indicator readability:

• Direct sunlight can overpower the illumination of some backlit indicators or produce glare on screens.
• Dim lighting conditions often make it difficult to read chassis labels and unilluminated status indicators.
• Water and dust can obscure lights or distort words. This effect may worsen when operators are required to wear protective eyewear.
• Some status indicators can be difficult to see off-axis, which can be particularly problematic for large control panels or in applications where operators are on the move.

These issues are best addressed by choosing status indicators with sufficient backlighting, an easy-to-wipe design, and a wide viewing angle. Designers can improve indicator readability while optimizing for space by integrating panel design elements, such as status labeling, into the indicators.

Saving space on the control panel through thoughtful indicator design

The status indicators can directly address some challenges of control panel design. For example, instead of having separate indicator lights near their labels on the panel, illuminated status labels save panel space by providing a single visual reference.

Similarly, swapping text labels with familiar icons can help operators quickly understand functionality, regardless of language proficiency. Icons such as battery charging status are universal and require less display space than phrases such as “fully charged” or “low battery.”

Further space conservation can be achieved by combining opposing notifications like “on” and “off” into a single indicator with distinct colors for easy differentiation. This allows designers to dedicate more visual real estate to important status notifications, instead of using multiple smaller single-status indicators that may be harder to see.

How dichroic LED indicators display multiple states

APEM created the Dual Icon series LED indicators to address these challenges. These devices incorporate advanced dichroic technology that enables a single indicator to switch between distinct red and green icons for a clear indication of the operating state.

Bright illumination and a 120˚ viewing angle promote high visibility under all lighting conditions. Their 14 millimeter (mm) diameter ensures that the icons can be readily identified at typical viewing distances. At the same time, their compact size helps save panel space through consolidated status notifications. The coated brass housing supports a maximum panel thickness of 7 mm with a D-cut shaft to prevent indicator rotation, which could otherwise lead to misinterpretation of certain icons.

To enable installation in harsh industrial or outdoor environments, the IP67-rated design offers comprehensive water and dust protection with a flat top for easy wiping. Additional ruggedization measures include:

• An operating temperature range of -30°C to 65°C, supporting rugged indoor and outdoor conditions
• Testing for 21 days of operation in 85% relative humidity to ensure reliability in agriculture and production applications
• Testing for 48 hours with a 5% salt spray solution to support reliable operation in maritime port and harbor equipment installations
• Shock resistance at 50 g for 6 ms half-sine pulse, enabling use in mechanically challenging industrial settings

Dual Icon examples

The Dual Icon series encompasses five indicator options, each available with three 200 mm wire terminations or solder lug terminals for installation at various distances from internal boards. The Q14F1BYYRG12E-DI101 and Q14F3BYYRG12E-DI101 (Figure 1) offer “I” and “O” status icons with solder lugs and wire terminations, respectively.

Figure 1: The Dual Icon Q14F3BYYRG12E-DI101 features green (I) and red (O) status indication and comes with wire terminations. (Image source: APEM)

These indicators can be used to show whether equipment or subsystems are turned on or in standby mode. Alternatively, these icons could indicate whether an interface is operating as an input (green, I), output (red, O), or unused port (unilluminated).

For direct on/off applications where positive confirmation of an off state is critical for safety reasons, such as industrial curing ovens or high-voltage power rails, the Q14F3BYYRG12E-DI102 (Figure 2) displays ON and OFF icons.

Figure 2: Shown are the three states of the Q14F3BYYRG12E-DI102 LED indicator: unilluminated, green (ON), and red (OFF). (Image source: APEM)

Conveyors, ovens, and compressors require START/STOP functionality for manual control. The Q14F3BYYRG12E-DI103 START/STOP indicator (Figure 3) can save panel space by displaying the current state of a single button serving both functions.

Figure 3: The Q14F3BYYRG12E-DI103 provides START/STOP LED indication for runtime controls. (Image source: APEM)

The Q14F3BYYRG12E-DI104 (Figure 4) is the first Dual Icon indicator to use pictographic icons, in this case for battery status and power “OFF” or “ON” state indication.

Figure 4: By leveraging the unilluminated state, the Q14F3BYYRG12E-DI104 can indicate an OFF or ON state in addition to battery status. (Image source: APEM)

This indicator supports a wide range of use cases, from charging stations to portable devices and small vehicles. By flashing either icon slowly, equipment designers can indicate that a battery is charging and provide an approximation of the charging progress to the operator. Alternatively, a rapid red flash on startup could show that the battery needs immediate charging or replacement.

Finally, the Q14F3BYYRG12E-DI105 (Figure 5) features opposing arrow icons that are useful for indicating the direction of conveyors when horizontally oriented, or for lift mechanisms when vertically oriented. For example, by coding “left” as green and “right” as red, the Q14F3BYYRG12E-DI105 offers at-a-glance direction identification from a distance.

Figure 5: By coding left as green and right as red, the Q14F3BYYRG12E-DI105 offers at-a-glance direction identification from a distance. (Image source: APEM)

Another use case for arrow icons is to indicate the side from which material will be ejected in specialized construction or agricultural equipment. This can be useful for safety checks when operating machinery near workers or obstacles.

Creating custom LED indicators for specialized applications

In addition to off-the-shelf indicators, APEM offers custom icon services that expand the possibilities for dichroic indicators in many industries. Whether used as two-state indicators via the green and red filters or three-state indicators by employing the unilluminated state, there is a wide range of use cases.

For example, a padlock icon is a globally recognized symbol that needs minimal explanation. A locked/unlocked-state indicator might be used in applications from security and access-control panels to driver-controlled bus doors. Alternatively, lock status indication can improve operator safety when working with machines containing material at high pressure or temperature.

Another example is plug and socket pictograms to indicate connection status. While this functionality can be achieved using the I/O indicator, specific icons promote faster recognition of status changes. Connection status indicators would suit applications such as modular agricultural and industrial equipment, where cables may become disconnected due to high levels of shock and vibration. In this way, custom icons support intuitive understanding of application-specific status changes to improve operator awareness.

Conclusion

The increasing complexity of equipment control panels requires thoughtful planning to support safety and efficiency in space-constrained applications. APEM’s Dual Icon series LED indicators use dichroic technology to provide two clearly distinguishable states via a single indicator while saving valuable space.