Comparing Motion Controllers and PLCs for Machine Control

When it comes to machine control, you may think you need to choose between a programmable logic controller (PLC) or motion controller. In many cases, the PLC does in fact eliminate the need to have a motion controller. And in others, the motion controller makes the PLC redundant and unnecessary by handling all the motion control tasks required for your application.

While it’s true you can reach for one controller over the other, there’s a third option that combines the two into a hybrid architecture—a setup that is typical of many high-performance machines. Let’s compare these various architectures so that by the end of this blog post, you’ll have a better idea of what you might need in your motion control application.

PLC Versus Motion Controller Machine Architectures

PLCs are machine controllers that also integrate motion and safety functions. In addition to the PLC itself, these architectures include the human-machine interface (HMI) and various sensors and drives. Although these setups are flexible, easy to install and reliable in industrial environments, they tend to have limited motion capabilities and processing power, as well as slower servo control sampling and update rates.

On the other hand, the motion controller is dedicated to motion control, making its motion capabilities much more expansive than that of the PLC. These machine architectures tend to integrate powerful processors and high-speed process execution and data acquisition. They also offer several advantages in terms of motion performance, such as greater repeatability, velocity control and settling time. In addition, motion controllers are well-suited for machines employing PC-based control and include more powerful profile generation and tuning tools.

The Best of Both Worlds: Hybrid Architectures

By combining the PLC and motion controller into one machine design, the hybrid architecture achieves new levels of machine and motion performance while offering many rich host application development tools. For example, by utilizing motion controllers from ACS Motion Control, you can unlock the following benefits:

Universal motor drive technology. Control various motors from the same motor drive including servo, AC/DC brush and brushless, voice coil, induction and stepper motors. Our drives also support incremental, analog and absolute position feedback signals, as well as dual-loop encoder feedback. Controllers and drives also have the ability to offer smooth on-the-fly switching between feedback signals. A single multi-axis ACS Motion Control drive can replace multiple third-party drives, reducing the number of vendors an OEM machine builder must use and support.

Expansive development tools. Using our feature-rich programming libraries, you can develop host applications using a programming language that’s familiar to you. As a result, you can more easily design your application with more capabilities, as well as a better front-end user interface and experience. A motion controller simulator even provides you with the tools you need to develop your application while reducing machine time. For example, this product enables your software engineers to define motion processes without having to reserve machine time on the product floor or wait for the arrival of purchased controllers.

Advanced control algorithms. You can also take advantage of our advanced servo control algorithms like ServoBoost™, which leverages powerful servo processor technology and modern control theory to outperform PID-based algorithms, as well as MotionBoost™, which generates advanced motion profiles that reduce vibration and settling time in sensitive applications.

And finally, you can unlock various inspection, metrology and automated optical inspection capabilities, such as the ability to incorporate autofocus sensor signals into sophisticated, real-time control algorithms. Other capabilities include:

• Position event generation for triggering cameras and lasers at high speeds.
• High-speed position capture (MARK) functionality with sub-microsecond latency.
• High-frequency data collection, enabling you to process and collect data up to 20 kHz.

To learn more about how we can deliver an ideal motion control solution for your application, please contact us.