We Still Should Remember the Nyquist Sampling Theorem
[Editor’s note: This is a response to Greg McMillan’s answer to this question in the Control Talk Blog.]
I have been a great fan of your work for quite some time. I don't see a lot of replies, as if this is a non-issue in the industry, or there is nothing else to say on the subject. Here is my two cents. When talking about PID sample rate, we still should remember the Nyquist sampling theorem. Even with the great advances of late in A/D conversion precision and input channel scan rates, a PID can still be fooled into controlling an alias signal given the right circumstances. The sampling theorem thus adds another low limit on the PID execution rate.
The tiny EZminiWiFi is a godsend for the plant maintenance engineers who need to make a minor modification to the HMI program or, for that matter, the PLC program. It's very easy...
Discover the benefits of American-made automation products, including stable pricing, faster delivery, and innovative features tailored to real-world applications. With superior...
Over the past 50 years, the automation technology landscape has changed dramatically, but many of the underlying industry needs remain unchanged. To learn more about what’s changed...
Watch EZAutomation's recent feature on the popular FOX Network series "Manufacturing Marvels" and discover what makes them a force to be reckoned with in industrial automation...