“Choosing an industrial computer or COM for industrial applications can save significant development time and unrecoverable engineering costs. Installing a circuit board into a control cabinet or enclosure with limited space requires knowledge of its form factor. We’ve covered common form factors that you might encounter during the selection process in this short article.
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By: Mouser Electronics Mark Patrick
Time to market is a key consideration for many industrial automation applications. But for some specific applications, where the most complex parts are increasingly implemented in software rather than hardware, this approach allows the use of commercial “normal” hardware computing platforms, of which many different types are available. However, system architects are faced with a dizzying array of form factors. Each form factor is based on a set of well-defined motherboard and module standards, providing design flexibility, competitive pricing, and secondary sourcing. This article will discuss some of the most popular form factors available for integration into industrial equipment designs.
Commercial computing hardware in the industrial field
At a high level, industrial process automation involves monitoring input from various sensors, processing the received data, and taking corresponding actions based on predefined workflows. Sensors may include limit switches, temperature, pressure, and motion measurements, etc., while control commands are executed through actuators such as relays, pumps, and motor drives.
The individual control areas form separate parts of the industrial process, each of which is equipped with a dedicated process controller. Hundreds of process controllers, typically consisting of single-board industrial PCs, can be deployed on a large manufacturing site, and while industrial PCs have essentially the same functionality as desktop PCs, there may be some notable differences. They will typically operate reliably over a wider operating temperature range, support industrial networking protocols and peripheral interfaces, and accommodate a wider range of operating systems. Not all single-board computers or computer-on-modules are suitable for applications requiring the -40 to +85°C industrial temperature range, and some boards are only compliant with the 0 to +60°C commercial temperature range.
The industrial market is not the only sector that requires general-purpose computing resources, with similar requirements in oil/gas, telecommunications, aerospace and defense, among others. For system builders, development complexity can be reduced by considering a variety of computer boards and modules from different manufacturers that conform to a set of mechanical and functional standards.
Dimensions
A set of open form factor standards has been developed to meet market demands. These provide single-board industrial PC and computer-on-module (COM) manufacturers with a focus in some specific markets, while open standards can provide system builders with the confidence of secondary sourcing and continuity of supply without having to redesign their systems .
Form factor standards determine the physical and mechanical layout of a motherboard, typically including power requirements, mounting hole locations, dimensions, and port layout. Many desktop PC motherboard form factor standards date back to the early 1980s and the advent of the IBM PC, and have continued to evolve since then.
Founded in 1994, the PCI Industrial Computer Manufacturers Group (PICMG) has more than 140 member organizations and has led the development of several important single-board computer and module standards. These standards are open, royalty-free, and require no license. PICMG standards include:
• Advanced TCA
• MicroTCA
• COM Express.
COM Express: The COM Express specification covers a range of small form factor (SFF) and COM type single board computers. COMs are typically designed to fit the baseboard (motherboard) power distribution and all I/O needs, this approach provides a quick and easy way to replace boards. Figure 1 shows a timeline of specification evolution and various form factors.
Figure 1: The evolution of the COM Express specification. (Source: PICMG)
The COM Express specification is also evolving to incorporate the latest processor technologies, storage methods, video interfaces and networking standards. For example, the COM Express Rev 3 specification accommodates up to four 10 Gigabit Ethernet interfaces on the board. A type declaration specifies the connector (one or two) and its pin usage in each specification.
ADLINK Express-CFR is a good example of a single board computer compliant with the PICMG COM R3.0 Type 6 specification.
Figure 2 illustrates the functionality of the board and the connector assignments for network, power, storage, and related peripheral interfaces.
Figure 2: ADLINK Express-CFR board complies with the PICMG COM.0 Rev 3.0 Type 6 specification. (Source: ADLINK)
The ETX Industry Group Association, the originator of the ETX form factor (embedded extension), has partnered with PCIMG to achieve compatibility of the ETX Rev 3 format with the COM Express specification. The ETX format remains a popular compact single-board computer form factor to this day. For example, the ADLINK ETX-BT is powered by an Intel Atom E3800 SoC that can accommodate up to 8GB of DDR3 RAM.
COM-HPC: The COM-Express specification limits two connectors to 440 pins. However, for new high-speed interfaces such as PCI Gen 4 with a bandwidth of 16Gbps, which is twice the bandwidth of PCI Gen 3, PICMG is required to develop a new specification COM-HPC. The specification defines three module types: client modules with fixed input voltages, client modules with wide input voltage ranges, and server modules with fixed input voltages.
The form factor of five COM-HPC boards has been determined: the smallest is dimension A, measuring 95 mm x 120 mm, and the largest is dimension E, recommended for servers, measuring 200 mm x 160 mm.
AdvancedTCA (ATCA): ATCA is another PICMG specification that is widely adopted in the telecom industry, which has a high demand for intensive processor resources, dense IO distribution, and high network bandwidth. Many military applications use ATCA hardened versions.
In addition to PICMG, the PC/104 consortium has established three different form factors. The first standard from which the consortium was named was the PC/104 form factor, which took its name from the 104-pin PCI connector, while other form factors from the consortium include the EPIC and EBX.
PC/104: This standard specifies a 90mm x 96mm board size and its mechanical design for rugged applications. This format allows stacking of multiple boards for applications requiring extensive I/O capability. An example of a PC/104 single board computer is the ADLINK CM1-86DX3, see Figure 3.
PC and manufacturer-derived form factors
Many industrial single-board computers continue to use the PC form factor established by desktop PC processor suppliers such as Intel and VIA. Examples include mini-ITX, Pico-ITX, and nano-ITX. Other embedded system manufacturers created formats such as UTX, which were then adopted by different vendors. MI/O is another example form factor developed by manufacturer Advantech.
Figure 4: Mini-ITX form factor comparison with Nano-ITX, Pico-ITX, and mobile-ITX specifications. (Source: VIA)
Mini-ITX: The mini-ITX specification defines a board size of 170mm x 170mm, see Figure 4. It was originally developed by VIA, one example of which is the Advantech AIMB-233, a fully functional motherboard with Intel i7, i5, i3 or Celeron cores that accommodates up to 64 GB DDR4 2,400 MHz SDRAM and features two M.2 storage slot.
MI/O: This standard was developed by Advantech and has two forms; Compact and Ultra. The Compact specification defines a slightly larger single-board computer than COM-Express, measuring 146mm x 102mm. The Ultra is the same size as the Pico-ITX board, measuring 100mm x 72mm.
An example of an MI/O Ultra board is the Advantech MIO-5272, see Figure 5.
Figure 5: Advantech MIO-5273 single board computer in MI/O Ultra form factor. (Source: Advantech)
The MIO-5272 is available for Intel i7, Intel i5, Intel i3 and Celeron variants. To support additional peripheral functions, Advantech has designed an expansion board format, MIOe, a unified expansion interface connector that provides power, USB 3.0, SMBus, DisplayPort, and PCIe connectivity for all MI/O form factor boards.
UTX: This single-board computer UTX form factor is 112mm x 137mm, examples of which include the Advantech AIMB-U233, an Intel 8th Gen-based motherboard with comprehensive storage, networking, and graphics capabilities. The board requires a 12VDC power supply, with a maximum power of 23W at peak load.
When time-to-market pressures do not allow a system-build approach, another available approach is to use off-the-shelf systems such as Advantech’s ROScube-I series. Ideal for robotics applications, this rugged embedded real-time controller offers GPU and VPU expansion cards for neural network algorithms.
Single-board computer-on-module for industrial applications
Choosing an industrial computer or COM for industrial applications can save significant development time and unrecoverable engineering costs. Installing a circuit board into a control cabinet or enclosure with limited space requires knowledge of its form factor. We’ve covered common form factors that you might encounter during the selection process in this short article.
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