HMI vs. IPC: What’s the Difference?

Differences Between HMI and IPC

            It is not a surprise that some people may be confused at the moment of choosing a monitoring system between Industrial PCs and HMIs. Apart from the technical differences, both devices look a lot alike despite of being quite different. Besides, both devices are fairly common in industrial environments nowadays, thanks to the increasing popularity and trust that IPCs have been gaining in the field. Of course, once there is knowledge about the feature set of each device, it is very easy to see what are their pros and cons.

HMI

            The job of an HMI is simple, it provides communication between the user and the machine. For this, the HMIs usually use a predefined communication protocol to share data with a PLC. Thanks to that, the HMI is able to translate the data coming from the PLC, and the commands sent by the user to the PLC. By today standards, the HMI are full of different features to reduce the time of installation without hitting all the functionality they can provide.

            HMIs have been in the industry for a long time, almost at the same time of the PLCs. They were an answer to the need of a better alternative to the old hardware-based control panels. But, at the moment of creation, they were not the same kind of HMI that we know today. They started by using a batch interface, which outputted data periodically depending on how it was programmed. In this case, the user wasn’t able to make decisions in the middle of a process.

            Following its development, then came the command line HMIs. Devices that, as the name implies, are built around a command line system which was capable of giving data on-demand. This was a great upgrade from the batch interface, which biggest disadvantage was that it wasn’t able to produce data on-demand.

            After that, the natural evolution of the industrial HMI brought the graphical user interfaces, a visual representation of the system, not only for outputs but for inputs. These graphical interfaces were highly customizable, so they were able to adapt to every system. Of course, there are some limitation, commonly seen in the side of the memory of the HMI or the number of variables that it was able to handle.

            One of the characteristics of an HMI, is that they are usually designed to be used only with a certain PLC of the same vendor. This can be a pro or con depending on the situation. It is possible to achieve connectivity with third party devices, but it would require unnecessary expenses on time and money. Besides, design software for these devices is locked as well into the same ecosystem created by the manufacturer.

            The aforementioned problem carries other problems, like the fact that a developer won’t be able to export any design made in one design software to another. This means, that in case of needing to change of manufacturer, the developers will need to redo all the graphical interface. It should not surprise anybody that this would add more expenses and development time to the project.

            HMIs are also characterized by their lack of advanced features, like multi-touch capabilities, high-performance processors, or better performing screens. This could seem a disadvantage for some users, but it is actually good in many cases. It diminishes the installation process time and the complexity in all of the device. Of course, there are more advanced and expensive options in the market, but everyone should be careful to the possibility of reaching a point where the price advantage over the IPCs is lost.

            And last but not least, the software of the HMIs is characterized by its closed environment. This means that users won’t be able to install new software by themselves. This also gives the advantage of having a more secure system, it is virtually impossible to insert malware to these devices.

Industrial PC

            If anyone is looking for the most powerful device, it is certainly this. IPCs are not only capable of providing graphical visualization of the system along with many advance features, but have the possibility of being a multipurpose device. It can actually work as an HMI and a PLC altogether. But as everyone should know by now, they have a huge disadvantage, these use an open operative system.

            This means that IPCs have installed operative systems like Windows and Linux, which are more susceptible to viruses or malware. For the standard of the industry, this is a great security problem, and it comes along to other problems like, frequent and unnecessary updates, major possibility of encountering bugs, the possibility of working with outdated software, and others.

            Since IPCs make use of high-performance CPUs and much bigger size of memory, they are capable of handling more complex pieces of software and hardware. They usually have larger screens with better resolution, are capable of handling much more data, they can use a great number of ports at the same time, and much more. They are basically an everyday computer in the industry floor. Of course, this comes at a price, IPCs are very expensive compared to their domestic siblings. Mostly, because of the need of more rugged and specialized hardware with certain focus in security, for both software and hardware.

Nowadays, it is still normal to see Windows 7 machines in some systems, but it is not recommended since Microsoft is not updating that version anymore. This situation is not strange, since in the field of automation, companies are always looking for long-lived solutions. Today, Windows 10 IoT is the operative system of choice for most people, it adds some security features that correspond with the necessities of the industry, and it is smaller than its commercial counterpart.

Another advantage worth noting from using IPCs over HMIs, is that since all the software are Windows-based programs, users are able to port almost every project from one device to another. This advantage decreases developing time in many cases, and most projects are ready to run with a couple of tweaks if they are already designed.

Conclusion

            At the end, there is always a spot for both systems in the industry. IPCs are a better choice for much bigger projects looking for a more advance solution, more sophisticated software, advanced data bases, larger sizes of memory, and more functionality. On the other hand, HMIs offer a cheaper solution for only monitoring a PLC, most devices are able to do everything most people would need from them, it is an easy way to monitor and control a PLC.

            It is worth talking about a new generation of HMIs that work with a more open approach, using web protocols such as HTML5. These devices are able to connect directly to a web server, similar to how a web browser does it. This allows the HMIs to connect not only to a PLC, but any device that is capable of transmitting data to a web server.

            At the end of the day, IPCs and HMIs are going to keep their relative spots in the industry. Since the latter can only fulfill one of the many functions that the IPCs are capable of doing, the selection will depend on the necessities, budget, and the time in which the project needs to be ready.

Tags: HMI, HMI vs IPC, IPC

This entry was posted on February 26th, 2021 and is filed under Automation, Education, HMI, IPC. Both comments and pings are currently closed.