Locking and Anchoring

Key Concepts

Locking and Anchoring are manual scheduling features that allow activities to remain scheduled at a specific time and/or on a particular resource when optimization is performed. Activities that are not locked or anchored are free to move around the schedule to accommodate the changes made by the optimization rules and options defined.

Lock

This command allows for activities to be locked to their currently scheduled resource. This feature is useful in cases where there are multiple eligible resources to perform the operation but you want a specific resource to be used. In addition, locking an activity will prevent it from being moved to another eligible resource during an optimize.

If an activity is locked, it cannot be moved to a different resource until first being unlocked. When an optimize is performed, the activity may move to a different time, but it will remain on the resource it was locked to. Locking an activity to a resource permits manual drag-and-drop scheduling changes to other times within that resource. 

To lock an activity:

  • The lock can be set to occur after an activity has been dragged and dropped by selecting the "Lock Activities to Resources after an activity has been drag-and-drop or Expedite". This option will only affect the activity block moved, leaving its successor operations to be moved freely by optimization.
                                   
  • Activities can also be locked immediately by right-clicking on an activity block, selecting "Lock to current Resources", and establishing at what level (Job, MO, Operation) of the activity you wish to lock.

               

  • In addition, jobs can be locked from the Jobs view by selecting a job and then clicking on the lock button in the toolbar, or by right-clicking the job and selecting "Lock" from the menu.

Note: Locked activities appear with a blue line at the top of the activity block in the Gantt.

Anchor

This command allows activities to be anchored to their currently scheduled times. During an optimization, the system will attempt to keep the activity scheduled to start as close as possible to the time it was anchored. It is possible that the activity will move out slightly later in time as optimization generates the schedule from the start of the schedule out into the future based on the optimization rules. This can result in the required resource to be unavailable to perform the activity precisely at the time it was anchored.

If an activity drifts out to a later time, then subsequent optimizations will continue to try to schedule the activity back to its anchor time to prevent it from drifting out too far. Activities that have drifted are outlined in yellow if the drift is within the same day, and highlighted in orange if the drift is to a different day. 

Note: Anchoring an activity does not prevent it from moving to another resource during optimization. Allowing the activity to be scheduled on alternate resources improves the chance of keeping the activity scheduled near the original anchor time. To prevent the activity from being assigned to a different resource, you can use the Lock feature in addition to anchoring. Although locking the activity will schedule it on the same resource, it will also increase the chance of drifting as fewer resources are available.

The more resource requirements an activity requires, the larger the drift is likely to be. This is because it will be harder to find a time when all required resources are simultaneously available to start the activity.

To anchor an activity in time:

  • The anchor can be set to occur after an activity had been dragged and dropped by selecting the "Anchor Activities in time after drag-and-drop or Expedite" from the Options button of the Gantt toolbar. 
                               
  • Activities can also be anchored immediately by right-clicking on an activity block, selecting "Anchor in Time", and establishing at what level (Job, MO, Operation) of the activity you wish to anchor.
             
  • In addition, jobs can be anchored from the Jobs view by selecting a job and then clicking on the anchor button in the toolbar, or by right-clicking the job and selecting "Anchor" from the menu.

Note: Anchored activities appear with a blue line on the left, right, and bottom of the activity block in the Gantt.