Beyond the box: Modern connectivity and the evolving control landscape

An embedded PC can often be found in customized machinery where a small form factor makes them suitable for specialized function. I ran across one of these just recently as part of a project to upgrade controls on an older, high-speed package sortation system.

The conveying system had two legacy SLC-500 cabinets, one for the upstream merge station and the second for the downstream takeaway conveyors leading to the shipping docks. The part in the middle was a sorting station that read packages entering the system and sorted them via 40 angle diverters. The packages were tracked via encoder from the point of entry all the way through the potential divert points.

Since packages were continually entering the sort station, the processor to keep track of all this would have to be capable of tracking packages and their drop-off points, as well as registering new packages as they arrived in the system. Due to the high demand of such a system, the vendor chose to use a dedicated, embedded PC with custom software to perform the task.

The above is a good example of how a PC can be used to perform the tasks that one might normally assign to a programmable logic controller (PLC). The embedded PC used Ethernet to communicate with a product from Opto 22 to provide inputs and outputs to the computer-based system.

Each I/O board had a module plugged into it, providing four points/channels of input or output. Depending on the module that was plugged in, the points could be ac or dc, input or output, normal or high speed. This technology still exists today with newer versions replacing the legacy systems found in the sortation system I encountered.

Another type of industrial PC is the box PC. This might have similar functionality to the panel PC, but the computer smarts are a stand-alone package that can be mounted in a suitable enclosure, and other peripherals like a screen, keyboard or mouse can be located elsewhere.

Some manufacturers of HMIs also offer this box PC type of package where you don’t have to have a screen at all to perform functions. These resemble a desktop PC but are very rugged in construction and are often fanless to live in harsh environments.

Some IPCs come as a DIN-rail mounted version. This format might be good for dedicated applications that are written in a higher-level programming language that is then compiled for execution. I recently came across such an application. The DIN-rail PC is loaded with a software application that interfaces with a programmable automation controller (PAC) and maps processor tags directly to and from an SQL/cloud database connection or IoT gateways that use OPC unified architecture (OPC UA) or message queuing telemetry transport (MQTT) for cloud transmission.

This was a game-changer for my employer at the time, as we had previously engaged a third-party software developer to custom-code an application that would watch for tags to change in our PAC and pass those events off to a flat file that our AS/400 system would digest and then print out labels to a label applicator for pallets of product.

Each new system we added cost us the same development cost as the original application. With this DIN-rail-mounted PC and the software interface, we were able to add as many of these print-and-apply systems to our operations as we wanted for just the cost of new printers for each line.

Some lines could be joined together by locating the DIN-rail mounted PC at a centralized point in our area of operations and having one IPC take care of multiple lines since each line PAC was connected to the same plant network as the AS/400 and the end of line printers. The cost saving per line was tens of thousands of dollars.

When the location of the PC requires greater separation from the process or where it might be interacting with IT equipment, the rackmount PC makes good sense. These are designed to fit in a standard industrial server rack and provide high-performance computing power. Applications in the utilities sector like nuclear, water treatment and de-salination control rooms would be places where this technology would be most appropriate.

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Any discussion about IPCs would be incomplete if we didn’t consider the proliferation of smart devices over the past few years. Industrial tablets are really IPCs with sizable computing power in a rugged enclosure and well-equipped to perform mobile tasks.

In the packaging industry, we started to see these being used for changeover tracking and field inspections. They are a huge benefit for inventory tracking in warehousing and distribution centers, and many operations are now using customized software on a tablet or smart phone for overall equipment effectiveness (OEE) metrics related to lean manufacturing.

In addition to availability, performance and quality elements, these same devices can be used to manage maintenance teams and activities, monitor and report utility performance and other such data collection.

One might even call a gateway module an industrial PC. In my continuing role as a converter of technology, the gateway module has been the difference between choosing a less archaic, but still obsolete, solution and committing to a fully modern solution for legacy equipment. For those familiar with the Rockwell Automation brand of products, the ControlLogix platform was a game-changer, not only because one could have more than one processor in a physical chassis, but one could also have multiple communication protocols in the same chassis and solution.

It was truly a gateway PLC/PAC. As happens with all technology, there comes a point where those older protocols come into disuse and the hardware vendors make the business decision to phase the modules out of production and, eventually, support. The gateway module presents a way to put the latest PLC platform into a legacy control system and still talk to the older devices on their native communications protocol. The gateway module is a mini-computer with the ability to connect via web browser or software application and map the old addressing into the new PLC- or PAC-based tags with a minimum of effort.

Industrial PCs are just as relevant as they were when first encountered 30-40 years ago. Application, environment and computing power still dictate where an IPC would be the right choice in a design solution. Niche solutions like the tag server are exactly where an IPC makes sense. There will still be situations where an IPC would be a better choice, even with the increased power and functionality of the PLC and PAC, but, it would seem, the lines between the choices have blurred and deserve consideration when designing a control system.