In this lesson, we are going to familiarize you with a process called a watchdog. In all computers, including PLC’s, there is a background process that ensures that the logic solve or processing of all of the needed functions occurs in a timely manner. We describe exactly how this background process functions and what happens if the watchdog determines that the logic solve is taking longer than is expected. We are also going to talk about scan cycle times. While connected, you can take advantage of one of the PLC’s diagnostics to determine how long it takes for the CPU to process your code from the beginning to the end. Let’s jump in a discuss watchdogs.