Open a control cabinet on any given factory floor, and there is a good chance that you will find some type of PC running part of the process, servicing cloud connectivity, processing images as part of a vision system or running a display panel. The modern industrial PC (IPC), although not immediately recognizable compared to the PCs of old, is a battle-hardened, rugged bit of hardware. But are they completely maintenance-free?
Original IPCs were a far cry from the industrialized versions now available. My first exposure to IPCs were in the form of 4U rackmount units that, although they looked tough because the housing was silver and had a threaded stud for channeling electrical noise to ground, they really just contained standard desktop PC components.
They did not fare well, it turned out, in the environment of a hot glass plant and required frequent parts swaps after something failed. Usually, the power supply would give up the ghost because of poor reference voltages or noise in the incoming power, or the fan, after becoming coated in greasy dust, would slow down and stop, and allow the rising internal temperatures to shut down the central processing unit (CPU).
IPCs now bear almost no resemblance to those earlier models. First off, they can be tiny due to the single-board nature of architecture. Secondly, the low-power CPUs that originated in notebook computers and other mobile devices lead to passively cooled, fanless models, completely sealed against the elements, even certified IP68 dust and waterproof.
Not only that, but fully potting a single-board computer in a passively cooled stainless-steel housing results in an IPC that can take nearly any vibration or shock that you can throw at it. I know of military applications where such IPCs are directly mounted to 50-caliber machine guns and other artillery, and they have no issues.
IPCs are physically tough and can be found as waterproof and dustproof units that are nearly bombproof. So, what are the Achilles heels of these units? As with any electronic devices, it still comes down to dust, moisture and input power quality.
Even though there are no moving parts to passively cool IPC units, dust can and will prevent proper cooling if allowed to accumulate in large amounts on the cooling fins of the heat sink. Fortunately, periodic dusting is all that is needed, and it is not nearly as frequently as older-style PCs with a fan. Months can go by without needing to brush or vacuum the settled dust off a unit without issue.
Even an IP68 waterproof PC has to have some type of connectors for power, fieldbus or video ports, antennae for wireless connectivity or universal-serial-bus (USB) ports. Any opening in the housing of an IP-rated IPC must have its factory-supplied sealed cover in place, or it will be an invitation for water entry, corrosion and failure of the internals.
The power supplies of modern IPCs are much more forgiving to supply voltage values, transients, electromagnetic interference (EMI), electrostatic discharge (ESD) and electrical noise in general than most other electronics, but you can still damage or shorten the lifespan of an IPC by supplying it with out-of-spec power values or by having large spikes in voltage. Some of this vulnerability can be mitigated by uninterruptable power supplies (UPS) and line filters on the incoming power.
If the IPC is supplied with a software image that includes a real-time operating system (RTOS) or real-time extension under Windows or even one of the Linux variants, this introduces some additional challenges to the owner. The factory IT department may pull the IPC in under their umbrella of computers that it manages and assume that automatic software updates, security patches and driver updates will make everyone’s life easier; after all, it is a PC, right?
Not necessarily. I have seen many real-time systems fail because the IT department pushed down software updates that result in issues to the performance of the system. Usually, the vendor-supplied driver set has been methodically tested with the real-time extensions, especially under Windows, to ensure proper operation with no memory leaks, locked memory blocks or anything else that causes issues with the system. In these situations, it is best to have IT treat the IPC as something other than a desktop computer and obtain software updates only from the original vendor.
IPCs have evolved into very rugged, stable devices that can function perfectly in extreme environments and provide fantastic performance. Are they totally indestructible? No, but with just a little care and forethought, they can provide years or even decades of reliable service.
