As with most other activities in Open Workbench, dependency relationships can be created or maintained in a variety of different ways. In this tutorial we will discuss a couple of the more common techniques.
The most common method is through the Task Properties dialog box. Select the Dependencies tab, and in the Project Tasks list, navigate to the task (or tasks) with which you want to create the dependency. Then, click on either Add Predecessor (to make the task a predecessor to the current task), or Successor (to make it a successor).
This will create the dependency relationship. When the relationship is created, the tasks will highlight in pink, indicating a dependency violation. Don’t worry about that – we’ll take care of it when we AutoSchedule.
The Dependencies grid in the Dependencies tab of the Task Properties dialog box has the following fields:
- Name – This is the name of the Task with which this Task has a relationship.
- Pred/Succ – This is the relationship type (is the Task a Predecessor to, or a Successor of, the current Task?
- Type – This is the Dependency Type, of which there are four:
- Finish – Start is the most common Dependency Type, in which the Successor Task cannot start until the Predecessor Task finishes.
- Start – Start is a relationship where the Successor Task cannot start until the Predecessor Task starts.
- Finish – Finish is a relationship in which the Successor Task cannot finish until the Predecessor Task finishes.
- Start – Finish is a relationship where a Successor Task cannot Finish until its Predecessor Task starts.
- Lag – Open Workbench uses Lag and Lag Type to determine the amount of time between two tasks, or the amount of time two tasks can overlap. Lag is a number that can be positive or negative, for example:
- if the value in the Lag field is greater than zero (i.e. a positive number), that is the amount of time, or a percentage of the duration (depending on the value in the Lag Type field) between two tasks. For example if you want Task 2 to start 3 days after Tas A finishes, make the Type = Finish – Start and enter 3.00 in the Lag text box (and Daily in the Lag Type drop-down).
- if the value in the Lag field is less than zero (i.e. a negative number), that is the amount of time, or percentage of task duration, in which two tasks can run concurrently. For example, if you want Task 2 to start 5 days before Task 1 ends, make the relationship Finish – Start and enter -5.00 in the Lag text box.
- Lag Type – Lag can either be represented in days, or as a percentage of task duration. The value in the Lag Type field determines this.
- Project – This is the name of the project of which the dependent task is a member. This is particularly important for inter-project (external) dependencies.
If you find an existing dependency relationship is incorrect or no longer required, you can safely remove it. To remove a dependency, select the row in the Dependencies grid (on the Dependencies tab of the Task Properties dialog box) and click Delete.
Be sure to check out our Beginner’s Guide to Open Workbench, which provides information on the features and functions of Open Workbench to get you started.