Industrial grade computing projects, including those involving rugged computers, monitors, or workstations, require appropriate connectors to ensure reliable performance in harsh environments.
Many engineers and integrators are familiar with everyday connectors like USB and HDMI for data or video, but industrial applications often require more robust solutions.
Connectors may need to withstand water, dust, vibration, and extreme temperatures, far beyond what standard office-grade ports endure.
In this article, we'll explore various connector types used in industrial and rugged computing and help you understand which might best fit your project's needs. We'll pay special attention to military-grade connectors like D38999, while also covering waterproof, rugged, and multi-cable connectivity options.
Bulgin is a well-known manufacturer of rugged, environmentally sealed connectors. Their Buccaneer series of circular connectors exemplifies how a connector can support common I/O signals in a waterproof form factor.
The Bulgin Data Buccaneer range includes sealed connectors specifically designed for Ethernet (RJ45), USB (including micro/mini-USB), USB-C, HDMI, and even RF/coax. These connectors carry standard protocols (for instance, Cat5e for Ethernet and HDMI 2.1 for video) but are built into robust IP67/IP68-rated housings.
Bulgin connectors often feature threaded locking mechanisms and come with protective caps, ensuring a secure, watertight connection in industrial, marine, or outdoor environments. If your project needs a plug-and-play solution for common interfaces (USB, LAN, etc.) but in a harsh setting, Bulgin connectors are a convenient option.
When extreme reliability is required, such as in military and aerospace projects, MIL-DTL-38999 connectors (often called D38999 connectors) are a top choice. These are high-performance circular connectors originally developed for the U.S. military, designed to withstand harsh environments, high vibration, and shock.
D38999 connectors are typically threaded and come in various series and sizes. They can accommodate a large number of contacts (many dozens of pins in one connector) for power, signal, and high-speed data lines. They are environmentally sealed, corrosion-resistant, and temperature-resilient, with versions capable of operating in extreme heat or cold.
Notably, D38999 is the prevalent standard for aerospace due to its quick coupling and anti-vibration design. If your industrial computing project must meet military standards or you simply need the highest durability, D38999 connectors provide proven performance.
Not all industrial connections use plug-style connectors – another approach is to use a conduit hub for cable entry. In this method, the device (computer or monitor enclosure) has a sealed conduit hub where a protective conduit attaches, and all cables run through that conduit. This effectively creates a single protected channel for multiple cables (power, data, video) to enter the enclosure without individual external connectors.
Conduit provides one of the best methods for routing, protecting, and sealing cables in wet or dirty environments, especially where cables might face physical abuse. For example, an industrial touchscreen monitor might offer a conduit hub option: instead of plugging cables directly into the monitor outside, you route the monitor cables through a flexible waterproof conduit that bolts onto the conduit hub.
The actual connections reside on the inside of the enclosure, safe from the environment, while the conduit and hub maintain the seal. This method is common in washdown areas or hazardous locations.
Roxtec develops flexible sealing modules that allow cables to pass through a cabinet or bulkhead while maintaining an environmental seal. These are not connectors in the traditional sense; instead, they are frames with modular rubber inserts that are tailored to the diameters of your cables. The inserts are compressed to form a tight seal around each cable.
Roxtec seals provide certified protection against water, dust, gas, fire, and even electromagnetic interference, depending on the configuration. In industrial computing, you might use a Roxtec entry panel on a large enclosure to bring in all required cables through one sealed opening.
This approach is common in industries like power utilities, marine, offshore, and telecommunications. It's a very high-density cable entry solution – useful when you want to avoid multiple drilled holes or external connectors. Also, a related solution to conduit entry is to use a multi-cable transit system, such as those made by Roxtec.
LEMO connectors are another category of high-quality connectors often encountered in professional and industrial equipment. LEMO is a Swiss manufacturer known for its push-pull locking connectors, which achieve a secure connection with a simple push and release with a quick pull.
These connectors are used in fields ranging from medical devices and test instrumentation to audio/visual equipment and aerospace.
LEMO connectors come in many series; for example, their K series offers IP68 waterproof push-pull connectors for outdoor use, and the 0B/1B series are common in lab equipment.
While not all LEMO connectors are "mil-spec," their M Series was developed for military and security applications, offering weight savings and high resistance to shock and vibration. LEMO connectors provide a reliable interface where frequent connect-disconnect cycles or space constraints exist – for instance, carrying a high-definition camera signal or a sensor feed in a research project, staying secure under tough conditions.
M-Series connectors refer to a family of metric circular connectors commonly used in industrial automation. Examples include M8 and M12 connectors, which have threaded locking rings (8 mm or 12 mm diameter) and are built for reliability in field applications.
M-series connectors are compact, sealed (often IP65/IP67 when mated), and resistant to shock and vibration.
They are widely used for sensors, actuators, and network connections on machinery. For instance, M12 connectors can carry industrial Ethernet as well as sensor signals or DC power on different pin configurations. M8 connectors are often seen on proximity sensors or small devices, typically carrying analog/digital sensor signals or CAN bus data.
The threaded coupling prevents accidental disconnection and maintains the seal under motion or vibration. If your project involves connecting to industrial sensors, PLCs, or distributed I/O blocks, M-series connectors are likely to be the go-to choice.
For harsher environments, waterproof connectors are essential. These connectors have Ingress Protection ratings (such as IP67 or higher) to prevent dust and water ingress. They are typically mounted on an enclosure and sealed with O-rings or gaskets to protect the device's interior.
IP67-rated connectors, for example, can withstand dust and brief immersion in water, making them ideal for outdoor or factory-floor equipment. The environmental sealing capability of IP-rated connectors makes them a great choice for industrial machinery, test equipment, and even offshore installations.
You might see IP67 connectors used where standard ports fail; they can be circular or rectangular connectors, sealed versions of RJ45 Ethernet jacks, USB ports with weatherproof caps, or ruggedized D-Sub connectors.
The key point is that a waterproof connector can carry the same signals (USB, Ethernet, HDMI, etc.) while protecting them from the environment. For example, an IP67 RJ45 jack provides standard Ethernet connectivity but keeps out water and dust.
Non-rugged connectors are standard on consumer and office equipment. Examples include USB Type-A/B/C ports for data, HDMI/DVI/DisplayPort for video, RJ45 Ethernet jacks for LAN, DB-9 serial ports, and so on. They are easy to use and widely available, but they are not designed for exposure to water or heavy dust.
In industrial settings, standard connectors are suitable only in controlled environments or inside protective enclosures. Many industrial PCs still offer standard I/O internally or in sheltered bays – for instance, a USB port or VGA output inside a cabinet.
If your project's environment is clean and dry, standard connectors might suffice. However, as soon as you introduce moisture, debris, or vibrations, it's time to consider ruggedized alternatives.
To clarify how these connector types relate to the signals they carry, the table below summarizes each category and examples of supported signal types. Keep in mind: a given connector's form factor often does not limit the signal protocol – for example, a waterproof circular connector could be wired for USB or HDMI, even if it doesn't look like a typical USB port.
Selecting the right connector for your industrial application is essential for continuous reliability and safety. Think about the environment: if there's a risk of water, dust, or vibration, choose rugged connectors or sealed cable entries rather than bare standard connectors.
Remember that a connector appearance has no bearing upon the signals it carries; you can have a USB connection (or a LAN link) via a round MIL-spec connector as easily as you might by way of a plastic PC port.
D38999 military-grade connectors represent the high end of ruggedization, but even within factory automation, rated solutions like M12 connectors or Bulgin's sealed ports often offer all the durability you need.
For projects with numerous cables or special sealing requirements, conduit hubs and Roxtec transits offer alternative ways to maintain enclosure protection.
Through knowledge of the connector types and what they can do, engineers and project managers can be assured that every connection in their system is up to standard, transmitting signals as the application demands, and impervious to the world of industry.
At VarTech Systems, our Project Managers—with an average of 15+ years of industry experience—are ready to customize a computer, monitor, or HMI workstation solution to meet your needs. Drawing from extensive backgrounds in manufacturing, military, oil and gas, and marine applications, they provide expert guidance throughout your project journey.
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Based in Clemmons, North Carolina, VarTech Systems Inc. engineers and builds custom industrial and rugged computers, monitors, and HMIs.
