Inspecting Task Links with BPC Logic Filter for Microsoft Project

BPC Logic Filter – an add-in for Microsoft Project (desktop) – includes an advanced Logic Inspector feature to greatly simplify the examination and navigation of logic-driven schedule activities.

When building or managing a complex project schedule, it’s often necessary to examine the logical relationships between tasks for a variety of reasons.  Particular questions for any given task include:

  1. What other tasks must finish (or start) before this task may start (or finish)? (i.e. what are its predecessors and how are they related?)
  2. Of all the task’s predecessors, which ones are actually controlling the scheduled dates for this task? – i.e. what are its driving predecessors?
  3. For the task’s non-driving predecessors, how much may each be allowed to slip before it becomes driving (for this task)? – i.e. what is the relative float?
  4. a)What other tasks must wait for this task to finish (or start) before they can proceed? – i.e. what are its successors?  b)Which successors are driven? c)How much relative float exists?

For users of Microsoft Project (MSP), questions 1 and 4a are most easily answered using the “Predecessors and Successors” view of one of the Task Forms in the lower pane.  For simple schedules, question 2 can be answered by the “Predecessors” list of the Task Inspector pane.  For more complex schedules – and for all other questions – the user must visually cross-reference the scheduled dates of the various linked tasks from several views, estimating relative floats and identifying driving relationships.  This can be time consuming and error prone.  Beginning with the 2013 version, MSP provides “Task Path” bar styles, which visually identify driving and non-driving predecessor and successor paths (i.e. logically connected task chains) of any selected task on the bar chart.  These can be difficult to read, however, when the project logic is complex.

BPC Logic Filter has always answered these questions on the way to visualizing logic flow through a schedule, and several of the tracer analyses can be easily customized to examine only a single task and its links.  Since the tracers generally apply a custom filter to the schedule, however, the time to examine a single task could become unwieldy for a very large project.

The native MSP predecessor and successor tables provide only limited information: ID, Name, Type, and Lag – all sorted according to the order the links were initially created.  Here they are shown as part of the Task Details Form.

Clicking BPC’s Logic Inspector creates two new floating windows listing the predecessors and successors of the selected task.

In contrast to the native forms, Logic Inspector provides a richer table: sorting the links according to relative float, highlighting driving links at the top of the table, and identifying links to inactive tasks at the bottom. Scheduled dates, Percent Complete, Total Slack, Task Calendars, and Resources of the linked tasks are also shown by default for easier confirmation and communication of relative float results.  (If desired, the latter two fields can be replaced by user-selected fields from the current task table.)

Logic-related fields for the selected task – Total Slack, Constraints, Deadlines, Start/Finish dates, Resources, and Calendar – are included for reference above the table.  Colored highlighting is used to emphasize those fields with notable influence on the current schedule.  E.g. effective constraints, violated Deadlines, Actualized dates, leveled resources.

The JUMP button allows logic-based navigation forward and backward through the schedule network one task at a time.  Jumping to another task using the button automatically updates the predecessor and successor forms.  Driving relationships are selected by default, but any relationship can be selected and explored.  To keep things simple, you can’t jump to a task that is hidden (by a filter or outline selection) nor to a task in another project window.  [Jan’19 Edit – this restriction was removed in version 1.5.]

Since implementation, I’ve found Logic Inspector to be an invaluable – and fast – complement to the rest of the features in BPC Logic Filter.  The two new windows are passive readers of existing project data; they are not for adding, removing, or modifying relationships.  MSP already provides a number of different approaches there.

Check out the video here to see the feature in action.

Using Logic Inspector to examine resource drivers is addressed in another post.

3 thoughts on “Inspecting Task Links with BPC Logic Filter for Microsoft Project”

  1. Logic Inspector is a great addition to an already powerful add-in. The predecessor and successor windows provide all of the information needed to understand the logical relationships on each activity. The JUMP buttons provide the ability to quickly trace and navigate through the schedule logic. Having Logic Inspector makes all the difference when trying to analyze the logic within a schedule.

    1. Thanks for the comment Chris. I’m glad you found this part of the tool useful. Although Logic Inspector was one of the last features added, I’ve found that it’s really at the core of being able to efficiently evaluate and communicate the logic that’s hidden in project schedules. It’s also nice to be freed from the overhead of generating filters in MSP just to inspect a few tasks.

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