Compared to an office computer, an industrial PC (IPC) must fulfill special requirements, which can vary greatly depending on the area of application. While 99% of office computers are based on x86 technology, an industrial PC is usually thought of as a computer with an x86 processor. And this certainly also applies to most industrial PCs on offer - which is often the right or best solution. However, if you look at the special requirements of an IPC, it is worth thinking outside the box.

ARM processors today are very similar to x86 processors in many functions, for example graphics, Ethernet and USB. On the other hand, ARM processors offer a whole range of special functions and some advantages, especially for the industrial sector. It is therefore well worth considering whether an ARM processor could also form the basis of an industrial PC.

The pros and cons depend very much on the given parameters. An essential part of the application is the application software: If this is Windows-based, there is hardly any way around an x86 solution. Up to now, systems other than x86 systems have only been insufficiently supported by Windows or a corresponding BSP (board support package) is always required, which makes it difficult to replace systems.

The typical areas of application for an industrial PC include industrial automation, robotics, process control and visualization, test benches for industry or safety technology and quality assurance. The application is often in a harsh environment, with extended temperature range requirements, dust and humidity. In addition, the devices are subject to increased shock and vibration values, for example when used in a factory hall with punching machines. An office computer, although inexpensive, will generally fail to meet these requirements.

Cooling of the system

The protection of an industrial PC against dust and moisture can be realized via appropriate housing technology and the relevant protection classes. The processor technology does not play a role here. However, if a system must have protection class IP65, another aspect comes into play: as the housing is largely closed, the heat dissipation of the system is particularly important. The less power loss a system generates, the more suitable it is for this application.

And this is where an ARM system clearly scores over a corresponding x86 system with comparable performance data. For example, a complete TQ mini module with an NXP i.MX6Q quad-core processor, which is used extensively, has a power consumption of around 4 watts, whereas an Intel Atom E3825 (BayTrail I) dual-core processor already has around 5 watts. Of course, it is possible to achieve a corresponding cooling of the system with appropriate measures - such as the use of fans, heat pipes or the outer walls of the housing designed as heat sinks. However, this always means higher costs and shorter life cycle times for the device. It therefore makes more sense to produce less power loss from the outset.

Extended temperature range

In many cases, the use of an industrial PC places higher demands on the temperature range. With appropriate measures, it is of course possible to run a standard system reliably in an environment with extreme temperatures. However, this may require extensive measures to keep the industrial PC operating within a normal temperature range. For example, the computer can be installed in an air-conditioned cabinet, in which case it will function reliably.

ARM and x86 architectures in direct comparison: While ARM processors score points for long-term availability, industrial quality and energy efficiency, the x86 shows its strengths in performance, graphics and storage.

© TQ-Systems

However, these measures come at a price. So why not use a system that can meet these requirements right from the start? Intel now supplies processors that are designed for these extreme temperatures, but not for all processors. ARM processors, on the other hand, are generally designed for such requirements and are also ahead in this respect. For example, all NXP ARM processors can withstand temperatures between -40 and +85 °C. In contrast, only the Intel Atom E3800 (Bay Trail-I) is available in the extended temperature range; the Intel Core 5000U (Broadwell-U) and Intel Core 6000E (Skylake-H) processors, on the other hand, can only be used at standard temperatures of 0 to +60 °C.

As already mentioned, industrial PCs are used in harsh environments, which means that the system is exposed to extreme mechanical shocks or vibrations. All connectors must be designed to be robust, which applies to all systems, regardless of the architecture. In addition, moving parts such as fans or hard disks should be avoided. A solid state disk (SSD), for example, is a good replacement for hard disks in harsh environments. Dispensing with a fan means a correspondingly sophisticated passive cooling solution.

As already described, this can lead to higher costs and a shorter service life for an industrial PC with an x86 processor. The internal structure also plays a key role. SO-DIMM memory is used in most industrial PCs. Although this offers a high degree of flexibility and the possibility of expanding the system by changing the memory bar, it is critical in terms of shock and vibration. Soldered memory modules are a conceivable solution and can be found in both x86 (with some providers) and ARM systems.

In industry, typical industrial interfaces are often found or required. These include all fieldbuses such as CAN or Profibus and serial interfaces. If a camera is connected, this can be done via USB or Ethernet/GbE. However, the camera must be equipped with the appropriate interface for this. But how is a camera with a direct camera interface connected? And what about connecting an LCD, which may well be required for panel PCs or HMIs?

Integrated interfaces

An x86 processor does not usually provide these interfaces. However, this is hardly a problem, as there is an abundance of providers and corresponding interface cards available for almost every task. However, such a system comes at a higher price and requires more computer space. And every expansion card is a further source of heat with the familiar problems. So why not use a processor that already has these interfaces integrated? There are a number of offerings on the market. The NXP Cortex A9 processor i.MX6, for example, already has two CAN, two SPI, up to four UART, one parallel display 24-bit, two camera, four PWM and up to 40 GPIO interfaces integrated. Further advantages are the significantly lower power loss, the lower system price and a smaller construction volume.

In some applications, the entire computer unit has to be accommodated in an extremely small space. One example of this is industrial PCs for top-hat rail mounting. Significantly smaller systems with similar performance data can be realized using ARM processors.

Long-term availability is a must

Another requirement from the industry is the long-term availability of the system and, moreover, the same design over many years. For example, 15 years is required for applications in the railroad sector. Although industrial PC systems with an x86 processor are often available with the same functions for many years, they are not identical in design. This means that system customization is necessary, which ultimately means time and costs. ARM-based systems can be supplied in the same design for a correspondingly long time due to the long-term availability of the processor if the supplier can also guarantee the same long-term availability for all other components of the system.

If the industrial PC only has to cope with fast data transfer and is used as a 'head-less' system, a completely different architecture may be the best solution. Processors based on PowerArchitecture from IBM or NXP are very often used in the telecommunications sector. So why not implement an industrial PC with a QorIQ from NXP? The system will certainly have significantly lower power dissipation at the same transfer rates and will be available for at least 15 years.

The system issue

All architectures have their advantages and disadvantages. In favor of x86 solutions are the high flexibility, the good interchangeability of the systems, the excellent graphics performance and the wide range of products. The range of software also speaks in favor of an x86 system. An ARM system can score points with its low power consumption, smaller dimensions, long-term availability and lower price. However, the software is a disadvantage here. The system always requires a special BSP and it is not so easy to switch to another, more powerful system, for example. There is no clear answer. It all depends on the application. TQ offers a modular system that contains x86 components as well as ARM and PowerArchitecture modules - as the basis for the customer-specific IPC solution.

Author: Wolfgang Heinz-Fischer, is in International Business Development for Embedded Products at TQ-Systems.