How scheduling works

Six activities, six links, one engine. Here is how a schedule gets its dates, its float and its critical path.

Each activity has a duration. Links say which one waits for which. That is all the engine needs. Columns, Scheduling, shows the engine's working: early and late dates, float, and the critical flag.

Early dates run forward from the start; late dates run backward from the finish. The gap is float. Free float is the slip an activity has before it delays the next one.

Total float is the slip it has before it delays the finish. Zero float means critical: delay these and the finish moves. Fabricate steel has three days in hand.

Longest path is the engine's other definition of critical: the chain with the least float to the finish. Change a duration and the pill says Unscheduled changes. In Fixed mode the engine waits for you.

Schedule now, or F9, runs the engine. After every run, What moved lists what changed and by how much. Keep them, or look closer.

Up to date. The long branch is critical, the short one has float; the finish moved a day. Filter, Critical only, keeps the chain that sets the finish.

Schedule options: Fixed waits for F9; Auto reschedules after every change. Simple mode is always Auto. The data date is where now is. Move it, and the engine schedules the remaining work from there.

Everything not started waits for the data date. Everything done stays where it was. A calendar decides which days count. On a seven-day, 24-hour calendar the same work finishes sooner.

That was the engine. Next in the Guide: links, the four kinds, and the lags and leads between them.

Taken from the video’s English captions.