Good morning Eduardo,

Thanks for your question.

In most applications, especially in discrete manufacturing, a single Continuous Task is used since no one part of the code has a higher priority than the other.

However, in many process systems it's common to have no continuous task, and instead have multiple periodic tasks, split between high-speed mission critical code and lower speed less time sensitive code.

Mission critical code often needs the extra speed to insure the safety of the working environment, or that of the equipment.

Lower priority code often includes code interacting with slow moving inputs, like temperatures and tank levels, as well as code that massages data for HMIs, Historians, and SCADA systems.

Hope this helps,

Shawn Tierney,
Instructor at The Automation School