Not exactly sure but I’ll give it a go. Typically when in the requirements gathering phase of a project you would like to break the large problem into smaller, more bite size type problems that you can code out. I’m guessing here, but if I had to code a large machine, I may be inclined to break that down into logical blocks or portions (or phases) and then each phase would have its own sequence.
If you’re referring to a PLC programming type paradigm, or style such as FBD, Ladder or SFC, I’m not familiar with phase or sequence.
Thanks for the reply, just curious more than anything, I recently did a project involving recipe manager for a factory, they asked me was I using phase or sequence logic. Sequence logic seems relatively self explanatory and your view on phase logic makes sense