Running and testing the control software brings the machines to life, but the type of software used and how it is written eases the birth, development and life of the machines.
With PLCs, the control software is closely tied to the hardware selected, but PC-based may offer more software options and features. However, industrial control software is starting to merge, enabling programming, HMI development and smart-device configuration on the same platform.
PLC control software remains tried and true
Since the day PLCs were born, control software has been closely tied to the manufacturer's hardware. If you bought the hardware, you bought the control software, except in rare case where it was free. It has been this way for well over 40 years.
Over the years, control software has been a profit center for the PLC manufactures. The control software from many of the top suppliers costs significant money. It also is available in various flavors for basic users, with just the minimal communication options and features, to professional developer versions. Support contracts for the software are also offered, in many cases at additional cost, especially if 24-hour support is required.
There is a reason the control software is tightly tied to the hardware. The control system and related control software must keep production running with high confidence. As long as the reliable integration and support of the control software with the hardware continues, the hardware manufacturers will have a tight hold on the control software.
A PLC vendor’s control software certainly is the master of the hardware it controls today. Even the low-cost leaders, whose control software is often free and quickly downloaded from the Internet, include very powerful software features and functions with the ability to control complex machines and processes.
As the complexity and requirements for the application increases, the higher-end and higher-cost PLC control software adds the ability to control multiple axes of motion and integrated safety and communicate with a wide variety of smart devices. This integration of motion, safety and communication is not guaranteed with all control software and should be carefully reviewed if required.
PC-based control is just another option
PC-based control software has been around for more than 25 years. Many thought it would replace the PLC and related control software, and some still do. This, of course, is not the reality today.
The PC-based control software is often sold as better than PLC control software in handle files, text strings and other data along with complex math, network collaboration and many other things, but both are pretty evenly matched when features and functions are compared. However, PC-based control software is still a viable option for many applications and often tied to the manufacturer’s hardware, as well.
Although some vendors tie the software tightly to the PC-based hardware, including very PLC-like controllers and rack-based I/O, others simply provide PC-based control software that will run on any appropriate PC hardware. Sticking with the PC-based control software that is closely tied to the hardware is often a good option. Letting the vendor carefully control the hardware and software reduces real-world issues with obsolescence and maintainability often seen with PCs.
Writing your own control software program using the high-level programming software of your choice is a bad idea for an industrial machine control application, unless of course you want to hold the customer hostage and ensure your job security. There are many great programmers out there—you know who you are—but, unfortunately, a lot of them come and go to greener pastures.
Many are also not as smart as they sound. and neither is their custom control software program.
Industrial hardware is driving machine control software. Don't be fooled into thinking that software is the driver. It's the controllers driving the boat. While the inexpensive embedded controllers, such as Raspberry Pi and others, seem like the greatest thing, they may not be an industrial strength or supportable option at this time, so be sure to start small with that, such as embedded control, and enjoy the wave if it comes.
If you have a small application, go with the PLC control software and PLC hardware—that's the basics. PLC control software is easy to use with great reliability, and it has been done that way for almost 50 years for a reason—it's a rock solid solution. Many PLC vendors are even offering low-cost control software and hardware options. It's a great choice and easy to learn.
As the requirements move into more of a plant standard arena, the control software must integrate well with the chosen hardware as a package. A continuing trend is to combine the control software, HMI software and smart device configuration software into one integrated package. It's great for efficient program development and as a control platform for an integrated solution. It can enable a connection to the IoT, which in the very near future will just be another feature of the control software.
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