The automation panels can be put in different modes depending on what you are trying to accomplish. We'll talk about the difference between the 3 in this article:

Auto:

This is the normal operating mode. In auto, the automation panel controls everything based on the preferences you have set. You won't be able to control any of your equipment from the pieces themselves because they only listen to what the panel says. Any changes you want to make need to be made there. 

Service: 

Turning the panel to service mode allows you to manually operate your equipment. Anything connected to your automation panel will need to be turned on at the unit itself if you want to run it. Sometimes its easier to go into "service" when you're backwashing or cleaning pump baskets to make sure nothing turns on unless you tell it to or if you want to test a piece of equipment. You can also just quickly turn the panel to service if you want to turn everything off. 

Timeout:

Timeout is just like service but after 3 hours it will switch back to auto. This is a great mode to use because if you forget to put it back in auto after doing something it will do it for you.