UK How COM Express modules and pin-out types work
COM Express is a PICMG standard (COM.0) for computer-on-modules: small boards that carry the processor, chipset and memory, and plug into a carrier board designed for the product. The carrier provides the connectors and any custom I/O. A module’s type is its pin-out, the agreed list of which signals appear on which connector pins.
Because the pin-out is standard, a newer module of the same type can usually replace an older one on the same carrier, upgrading performance without redesigning the system. That is the main reason COM Express is used in medical, test, transport and defence equipment with long product lives. The type has to match: a Type 7 module will not work on a Type 6 carrier, even though the connectors are physically the same.
The main pin-out types
PICMG has defined several types since the first release in 2005. Revision 2.0 in 2010 added Types 6 and 10 and retired most of the earlier ones, and Revision 3.0 in 2017 added Type 7. Three types cover nearly all new designs.
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Type 6. The general-purpose pin-out, for machines with screens, cameras and mixed I/O. It provides up to 24 PCIe lanes, three digital display interfaces, USB 3 and SATA, plus Gigabit Ethernet.
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Type 7. A headless pin-out for networking and edge server workloads. It drops the display interfaces in favour of up to four 10GbE KR ports and up to 32 PCIe lanes.
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Type 10. A reduced pin-out on a single connector, used mainly on Mini modules for small, low-power devices, with fewer PCIe lanes and one display interface.
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Type 2 and older types. Earlier pin-outs with legacy PCI and parallel ATA. Type 2 survives in long-running designs but is not recommended for new ones.
How Type 6, Type 7 and Type 10 compare
The table summarises the three current types. Exact counts depend on the processor on each module, so check the module datasheet for what it actually brings out.
| Feature | Type 6 | Type 7 | Type 10 |
|---|---|---|---|
| Connectors | Two 220-pin (440 pins) | Two 220-pin (440 pins) | One 220-pin |
| PCIe lanes | Up to 24 | Up to 32 | Up to 4 |
| Display outputs | Up to three DDI plus eDP or LVDS | None (headless) | One DDI plus eDP or LVDS |
| Ethernet | 1 GbE | 1 GbE plus up to four 10GBASE-KR | 1 GbE |
| Usual sizes | Compact and Basic | Basic | Mini |
| Typical use | HMI, medical imaging, vision, test | Network appliances, edge servers, storage | Handheld, portable and low-power devices |
Revision 3.1, published in 2022, brought PCIe Gen 4 and USB4 to the standard, so recent Type 6 modules can carry current processors at full speed.
Module sizes
Size is set separately from type. The standard defines four footprints: Mini at 84 × 55 mm, Compact at 95 × 95 mm, Basic at 125 × 95 mm and Extended at 155 × 110 mm. Compact and Basic balance size against room for the processor, memory and heat spreader, and are the most common sizes for Type 6. Mini modules usually use the Type 10 pin-out. Extended modules are now rare.
A Type 6 module of any size fits a Type 6 carrier designed for that size, and many carriers accept both Compact and Basic modules through alternative mounting holes.
What the carrier board adds
The module is only half of a COM Express system. The carrier board turns the signals on the module connectors into a working product, and it is where most of the design effort goes.
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Power input. The carrier converts the supply, often a wide-range 9 to 36 V DC input in industrial designs, to the 12 V most modules expect.
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Real connectors. Display, USB, Ethernet and serial ports are placed where the enclosure needs them, including locking or M12 connectors.
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Custom I/O. Fieldbus, isolated digital I/O, extra network controllers or M.2 slots can be added to the PCIe lanes the module provides.
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Thermal path. The module’s heat spreader is a standard interface, so the carrier and enclosure can conduct heat away without a fan.
Choosing a type for a new design
Start with the I/O the product needs. If it drives displays, takes camera inputs or needs general USB and SATA, Type 6 is almost always the answer, and it has the widest choice of modules from Intel Atom and Celeron through Core and Core Ultra to AMD Ryzen Embedded. If the product is a network appliance or an edge server with no local screen, Type 7 gives far more Ethernet bandwidth and PCIe. Type 10 suits small battery-powered or handheld devices.
If the design needs more bandwidth than COM Express offers, such as many PCIe Gen 5 lanes, 25GbE or very high memory capacity, COM-HPC is the next standard up. Our COM-HPC vs COM Express comparison shows when to move, and our system-on-module explainer covers the module-and-carrier approach in general.
We stock COM Express modules and systems, ready-made COM Express SBCs that pair a module with a standard carrier, and COM Express carrier boards for custom builds. Our reverse vending case study shows a Type 6 design in service.
Quick answers on COM Express types
COM Express module types: common questions
What is COM Express Type 6?
The most common COM Express pin-out. It provides display outputs, USB, SATA, Gigabit Ethernet and up to 24 PCIe lanes, for embedded systems with screens and general I/O.
What is the difference between Type 6 and Type 7?
Displays against networking. Type 6 brings out display interfaces. Type 7 drops them and adds up to four 10GbE ports and more PCIe lanes for headless edge servers.
Are COM Express types interchangeable?
No. A module only works on a carrier designed for its type. Within one type, newer modules usually drop in to replace older ones.
What is COM Express Type 10?
A reduced pin-out for small modules. It uses a single connector and is used mainly on Mini modules for low-power and portable devices.
Is COM Express being replaced by COM-HPC?
Not for most designs. COM-HPC adds bandwidth for high-end systems, while COM Express continues for the mid-range, with new modules still being released.
We supply COM Express modules fitted to their carrier, with memory, storage and the operating system installed as standard, and help match the module type and size to your design.