Link Unlink Tasks

Online Help > Link Unlink Tasks

After tasks are linked to create task dependencies, you can easily change or remove the dependencies, if needed.

In most cases, the tasks in a project are related to each other, and the relationships between them drive the schedule for the project. The relationships between the tasks are called "dependencies." Typically after the tasks were inserted in the project and the WBS structure was created, the next step is to link the tasks among each other, to show relationships between them.

While building a project plan, you may encounter situations when a task can start only after another one is completed. I.e., you want to furnish the room only after the walls are completely painted.

Tasks scheduling is performed based on duration estimates of each individual task and tasks interdependencies that constrain a task to start only after other tasks in the project have been completed.

After introducing the WBS and duration estimates for each task, you have to introduce the interdependencies among tasks.

The constraint in the example above (furnishing after painting), corresponds in Project Plan 365 to a Finish-Start constraint.

Other constraints can be imposed in Project Plan 365 as well. I.e. for building a foundation you may start levelling the concrete once the concrete started to be poured. This corresponds to a Start-Start constraint.

Such constraints that involve two tasks and condition the start/finish date of one task on the start/finish date of the other task, are imposed in Project Plan 365 by creating links between tasks. By linking tasks Project Plan 365 adjusts the schedule whenever there are changes that affect duration of other tasks.

A task that needs to be completed before is called a predecessor task and the linked tasks are its successors.

Besides specifying the type of dependency between two tasks, you can also indicate a lag value, which can be either positive (lag time) or negative (lead time). You can enter lead time or lag time as a duration. You enter lead time or lag time on the Predecessors tab in the Task Information dialog box. Also you can quickly add lead or lag time to a successor task by typing value in the Predecessors column. 

What is a “link” between tasks?

A link between tasks or a dependency is a relationship between tasks.

What is a Successor?

A successor is a task whose start or finish date is driven by its predecessor task. The Successor is the task completed after the current task.

What is a Predecessor?

A predecessor is a task whose start and finish date determines the start or finish date of its successor task. The Predecessor is the task completed prior to the current task.

What is Successors field?

The Successors field lists the task ID numbers for the successor tasks to a task.

What is Predecessors field?

The Predecessors field lists the task ID numbers for the predecessor tasks on which the task depends before it can be started or finished.

What is Lag time?

Lag time is a delay between tasks that have a dependency.

For example, if you need a two-day delay between the finish of one task and the start of another, you can establish a finish-to-start dependency and specify two days of lag time. You enter lag time as a positive value.

What is Lead time?

Lead time is overlap between tasks that have a dependency.

For example, if a task can start when its predecessor is half finished, you can specify a finish-to-start dependency with a lead time for the successor task. You enter lead time as a negative value. To enter lead time, type a negative value in the Lag column, such as –2 for two days of lead time.

What are the supported link types/dependencies?

The supported link types are: Finish to Start (FS), Finish to Finish (FF), Start to Start (SS), Start to Finish (SF).

What is Finish-To-Start dependency?

The Finish to Start dependency is the default link type applied. It forces a task to start only when/after its predecessor has finished; predecessor finishes and the other starts.

A link can also have a "lag" value specified. Finish-to-start is the most common dependency type. If a nonzero lag is present, it is added to the Start date; otherwise, the task starts immediately after the predecessor is completed. A positive lag value will create a gap between the finish of one task and the start of another.

 The dependent task (B) cannot begin until the task that it depends (A) on is complete

What is Finish-To-Finish dependency?

The Finish to Finish dependency forces a task to finish only when/after its predecessor is completed; both tasks finish at the same time. If a nonzero lag is present, it is added to the Finish date.

For instance, a value of 4FF+2 days in the Predecessors column signifies a Finish - Finish type link with a lag of two days, where the current task has the task with ID = 4 as its predecessor.

 The dependent task (B) cannot be completed until the task that it depends on (A) is completed.

What is Start-To-Start dependency?

The Start to Start dependency forces a task to begin only at the same moment with its predecessor or after its predecessor started; the start of the predecessor determines when the other starts. If a nonzero lag is present, it is added to the Start date.

 The dependent task (B) cannot begin until the task that it depends (A) on begins.

What is Start-To-Finish dependency?

 The Start to Finish dependency forces a task to finish only when/after its predecessor start. If a nonzero lag is present, it is added to the Finish date.

 The dependent task (B) cannot be completed until the task that it depends on (A) begins.

My project plan does not take limited ressource into account, means 2 tasks remain in parallel with only 1 ressource allocated 100%. How can I plan my project automatically with limited ressources?

Project Plan 365 app will not move your task automatically if you have the same resource on two parallel tasks. The application tells you that you have an overallocated resource by making the entire resource font with red in Resource Sheet view. If you want tasks to be in sequence, you need to link the tasks and specify a predecessor.

How can I link two tasks?

To establish a relationship between two tasks or link two tasks click on the task that will be dependent and go to Task Information – Predecessors – select the task that will dictate the relationship and the type of link between them – click OK.

Another way is to enter the ID of the task in the Predecessors field or you could also select the predecessor from the field's drop-down list. By selecting the ID it automatically creates a Finish-To-Start link from the predecessor to the current task or you can enter the ID of the predecessor followed by the link type - a value in {SS, SF, FF}.

Is there a way to have a task begin X number of days before another task ends or begins?

To have a task begin X number of days before another task, you need a lead time. Lead time is overlap between tasks that have a dependency.

For example, if a task can start when its predecessor is half-finished, you can specify a finish-to-start dependency with a lead time for the successor task. You enter lead time as a negative value.

Let’s say you have two tasks. Task ID 1 with a duration of 5 days and Task ID 2 with a duration of 3 days. You want that task ID 2 starts with 2 days before task ID 1 ends. In the Predecessors field, we establish a Finish-To-Start dependency and set the lead time -2days: 1FS-2days.

How to make a task start after another task?

To make a task start when another task is finished, you need to establish a Finish to Start dependency in Predecessors column or in Task Information dialog under the Predecessors tab.

How do I make a start to start relationship between tasks?

To make a Start-to-Start relationship between tasks, you need to establish a Start to Start dependency in the Predecessors column or in Task Information dialog under the Predecessors tab. For example, you have task ID 1 and task ID 2 and you want to establish a Start-to-Start dependency. In task ID 2 on Predecessors columns write 1SS.

How to add a start to finish dependency?

To add a start to finish dependency between tasks, you need to establish a Start to Finish dependency in the Predecessors column or in Task Information dialog under the Predecessors tab.

How do I add a predecessor?

To add predecessors to tasks, go to Gantt Chart view and in Predecessors field insert the Task IDs or select the predecessors from the field's drop-down list.

How do I edit the Successors field?

We are sorry, but at this point, you cannot edit the Successors field. You can only specify the Predecessor for a task.

Where is the Link button to schedule the tasks?

The Link button is under the Task menu.

How do I unlink a task?

To unlink a task, select the desired task and then go to the menu Task - Unlink.

What does FS mean?

FS is an abbreviation for Finish to Start dependency. It forces a task to start only when/after its predecessor has finished; predecessor finishes and the other starts.

How do I see the overall duration of tasks including predecessors?

To see the overall duration of tasks and predecessors, in Gantt Chart view insert the Duration and Predecessors column. To achieve this, go to menu Format - Insert Column.

How to unlink two tasks?

To unlink two tasks, please delete or uncheck the Task ID from Predecessors column, or select both tasks and go to menu Task - Unlink. To change the Start date for a
task, please make sure that the % complete is set to 0.

What is a Task Dependency?

It is a relationship between the tasks in the project that drive the schedule for the project. The nature of the relationship between a predecessor task and a successor task determines the type of task dependency to use. We can use 4 types of task dependencies: Finish - To - Start (FS), Start - To - Start (SS), Finish - To - Finish (FF) and Start - To - Finish (SF).

Why I can’t see the “Link” button in ribbon on the Mac platform?

If the “Link” button is not visible in ribbon, please press  "More" button. You should be able to find in the dropdown the button that doesn't fit inside the ribbon because of the small window size.

Why I can’t see the “Unlink” button in ribbon on the Mac platform?

If the “Unlink” button is not visible in ribbon, please press  "More" button. You should be able to find in the dropdown the button that doesn't fit inside the ribbon because of the small window size.

How can I add Hammock Tasks?

We are sorry but we don't support hammock tasks at this point.

What does the “Help” button inside the “Predecessors tab – Task Information dialog” do?

The “Help” button inside the “Predecessors tab – Task Information dialog” redirects us to the “Link Unlink Tasks” article in our Online Help page.

Is there a way to start tasks when the other task is 50% complete?

In the Predecessors column you can set the Predecessors with a Start-to-Start dependency an then add the lag time. Example: 4SS + 5days.

Step by step on how to link or unlink tasks:

1. In the Gantt Chart View, select the desired task. Go to menu Task - Task Information.

2. In the Task Information dialog box, click on Predecessors tab.

3. Select the task that will be linked as well as the constraint type and click OK.

You can also link two tasks by inserting the Predecessors column. You can:

  • write the ID of the predecessor or select it from the cell's drop-down list; this automatically creates a Finish-Start link from the predecessor to the current task
  • write the ID of the predecessor followed by the link type - a value in {SS, SF, FF}

Using a vertical drag-and-drop operation starting from the predecessor: implicitly a Finish-To-Start link is created; to change the link type or to delete it, perform a double click on the link.

By using the Link option under Task menu, which creates a Finish-To-Start type of dependency between the two selected tasks.

Note: After tasks are linked to create task dependencies, you can easily change or remove the dependencies, if needed. To remove a link between two tasks, either remove the value from the Predecessors column or press on Unlink option from Task menu.

Avoid using too many complex links; it makes the project less manageable and the schedule more difficult to interpret.

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