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Scheduled Start Field for Manually Scheduled Task does not always honor Predecessors RRS feed

  • Question

  • I am learning about how manually scheduled tasks behave and am reviewing an opportunity for their use when developing a new schedule from scratch.

    I read the documentation on the new 2010 Scheduled Start/Finish fields.  The documentation states:
    Project calculates the Scheduled Start field based on task dependencies, constraints, the project calendar, and any task calendars.  If resources are assigned, Project also considers the resource calendar and assignment units.

    This sounds great!  It sounds like if I have a notional schedule, I can start with manually scheduled tasks and then add logic and durations iteratively.  The Scheduled Start/Finish fields will honor the duration and logic even if the Start and Finish fields for the manually scheduled tasks have not yet been populated.

    Unfortunately.....I do not see this behavior in the MS Project 2010 application.  If I link three manually scheduled, 5 day tasks in a chain together and then review the Scheduled Start/Finish dates I get very confusing results.  Task 2 has a Scheduled Start after the Scheduled Finish date of Task 1 (expected), but Task 3 has the same Scheduled Start date as Task 2 (unexpected!).  Task 3 should have a Scheduled Start after the Scheduled Finish date of Task 2 (it's logical predecessor).

    Very confused in Tewksbury, MA.

    Thanks,

    Michael Trilling

    Raytheon Company

    Wednesday, June 25, 2014 3:20 PM

All replies

  • Michael,

    You indicate you have Project 2010 but do not mention whether you have SP2 installed. If you do not, then install it. I also recommend you install the June 2013 cumulative update as it was released after SP2 and fixes several significant issues.

    With regard to your example, I set up three tasks as you describe. When I look at the Scheduled Start and Scheduled Finish dates, all dates are as expected (i.e. start of task 2 follows finish of task 1 and start of task 3 follows finish of task 2). I am using Project 2010 Pro with SP2 and the April 2014 cumulative update.

    John


    Wednesday, June 25, 2014 4:18 PM
  • If you select all 3 tasks and click "respect links" on the Task Ribbon does everything update as expected?

    Is there any progress (% complete or actual start date) on task 3?

    Wednesday, June 25, 2014 6:03 PM
    Moderator
  • Yes, but that also has the effect of populating the Start and Finish fields which "peg" the tasks on those dates.

    The Scheduled Start/Finish dates should calculate correctly regardless of the Start and Finish dates.  If the duration should change on a predecessor task that had the "respect links" done to it, the Scheduled Start and Finish dates should ripple through.

    There is no % Complete or Actual Start on any task

    Wednesday, June 25, 2014 6:21 PM
  • Hi John,

    I am at SP2 (I am not aware of an SP3 for MS Project 2010).

    I have tried the April 2014 and the latest June 2014 CU and see no difference.

    Are you sure your experiment used Manually Scheduled Tasks?  If you have Auto Scheduled Tasks, you will see the correct calculations in both the Start/Finish as will as the Scheduled Start/Finish fields.

    Michael

    Wednesday, June 25, 2014 6:24 PM
  • Michael,

    Oops, my first reference to SP3 was a typo. I have since corrected that.

    This is how I set up the test file.

    1. File/New

    2. Set Task Mode to Manually scheduled for 3 lines (no other entries yet). I did this because my option setting is for auto-scheduled tasks.

    3. Entered task name and then a duration of 5d for each

    4. Selected all three tasks and hit the link icon

    Is your file one you've been playing with for a while? If so, it may be corrupted. Close Project, open again and try a fresh new file. Does that work?

    John

    Wednesday, June 25, 2014 7:02 PM
  • Hi John,

    I think you probably have the following options set in the Schedule section:

    Update Manually Scheduled tasks when editing links: checked

    Calculate project after each edit: On

    These settings will cause the Start/Finish Dates to be populated when you click the link icon.  This changes the task from being a Placeholder task to a non-Placeholder task.

    In addition, if you change the duration of Task 1 to 20 days even with the settings presumed above, the Scheduled Start/Finish dates for Task 3 will again become incorrect.

    Still perplexed in Tewksbury, MA.

    Michael

    Wednesday, June 25, 2014 7:21 PM
  • Michael,

    Let's go back to your initial post where you quoted from the help file on Scheduled Start/Finish fields. Yes, for auto-sheduled tasks, the Scheduled Start and Finish are calculated based on predecessors, calendars, etc. However, read the part about how the Scheduled fields are treated when using manual scheduling. It states that the Scheduled fields are recommended and read only.

    When you change the duration of the first task, the Scheduled Start date does indeed change to what would be "recommended" due to the link. However, since the second task has not in fact moved, because you are still in manual schedule mode, the link between task 2 and 3 reacts to the existing dates (i.e. Start and Finish, not Scheduled Start and Scheduled Finish). It should be noted that after the duration of task 1 is changed, the Gantt Bar for task 2 shows a potential scheduling problem, so the user if being alerted.

    I think everything is consistent but it takes some getting used to. Now, are you really sure you want to use manual scheduling? I personally don't have a lot of use for the manual scheduling mode but I guess that once you get the hang of it, it could potentially be useful for setting up a schedule outline.

    John

    Wednesday, June 25, 2014 8:52 PM
  • Are we to guess that you have those options off?

    Project Pro 2010 SP-2 and the April 2014 installed here's what I see.

    1. I have turned off the option "Update manually scheduled task when editing links." However, Calculation is on.
    2. Created a new project with manually scheduled tasks.
    3. Project Start date set to 23 June.
    4. Added 3 tasks A, B, C.
    5. Scheduled start for all 3 tasks 23 June.
    6. Scheduled finish for all 3 tasks 23 June.
    7. No Start or Finish dates.
    8. Changed duration for all 3 tasks to 5 days.
    9. Scheduled start for all 3 tasks 23 June.
    10. Scheduled finish for all 3 tasks 27 June.
    11. No Start or Finish dates.  So, all 3 tasks are still "placeholders" as you call them.
    12. Linked task A to B.
    13. Task A Scheduled start 23 June, Scheduled Finish 27 June. No start or finish dates.
    14. Task B scheduled start 30 June, Scheduled Finish 4 July. No start or finish.
    15. Linked Task C as the successor to Task B.
    16. Scheduled start for C 30 June, Scheduled Finish 4 July.  No start or finish.
    17. Change the duration of task B to 20 days.
    18. Scheduled Finish of B is 25 July.
    19. Scheduled start of task C 21 July.
    20. Unexpected result. However, the predecessors field has schedule warnings for task B and C.

    I guess I'm not following what you are trying to do and why the Start and Finish fields populating are of concern.

    Wednesday, June 25, 2014 8:53 PM
    Moderator
  • I don't follow what you mean by "peg" the task. The start and finish dates of manually scheduled tasks can be changed at any time and do not update automatically after the first link.
    Wednesday, June 25, 2014 8:55 PM
    Moderator
  • Hi John and Julie,

    First of all thanks for all of the timely responses today.  Very impressive support.

    I did take note of the word "recommended".  I think it a very odd word choice.  The "recommendation" is certainly based on a logical algorithm, no?

    If the crux of the argument is that manually scheduled tasks are too confusing to use and therefore we should not use them, then I am even more perplexed as to why it was added into 2010 at all.

    To me, the fact that there are calculated start/finish fields in addition to the user input start/finish fields shows that the idea is to lead the schedule developer through the process of building up a logically linked schedule by slowly adding information as it becomes available.  The new 2010 fields "Placeholder" and "Warning" are, I am convinced, intended to focus the schedule developer on those tasks requiring better scheduling information.

    At the end of the process of eliminating all of the placeholders and warnings and manually scheduled tasks, the schedule will be "clean".

    I can't fathom any other meaning for the "recommended" Start and Finish of a task other than the one outlined in the documentation.  It must be based on everything currently known about the network of tasks.  How can the "recommended" Start of a task be anything other than the latest "recommended" Finish of its predecessors?  Anything else seems totally pointless and void of value.

    Thanks again for the dialog.

    Michael

    Wednesday, June 25, 2014 9:27 PM
  • I don't believe manually scheduled tasks are "too hard to use."  They certainly have their quirks, but by-in-large the quirks are understandable.

    If you simply enter a task without start, finish, or duration the Scheduled Start will equal the start date of the Project.  The Scheduled finish will be start date + the default duration of one day.  If you enter duration in a manner that Project understands, the scheduled finish is recalculated.  If you have the options of Update manually scheduled task when editing links on and you link the manually scheduled tasks - the tasks work just the same as autoscheduled - initially.  The schedule warning are there as just that - warning that may be ignored, just like overallocation warnings.

    I think manually scheduled tasks are good for folks fairly new to a scheduling product - perhaps those coming from Excel.  However, I agree that autoscheduling is the best option at the end.


    (By the by, John and I are volunteers - not paid by nor affiliated with Microsoft. As such, we really can't do more than speculate about the "why" of how the product is designed.)
    Wednesday, June 25, 2014 9:47 PM
    Moderator
  • Michael,

    I think Julie's statement about us understanding all the reasons why Project was designed the way it was, is a good one. I believe the manual schedule mode was added because users, particularly new users, had problems getting their heads around the apparent hard and fast scheduling, they wanted more "fuzzy" functionality. I won't say the manual scheduling feature was poorly designed but it does take some time to learn. Maybe I have a harder time with it because all my Project experience has been with the auto-scheduling.

    I guess in the end you just have to experiment with manual scheduling and see if it looks like it will be useful to you. I wouldn't get to hung up on the dates and whether the Scheduled fields always track with the normal fields.

    John

    Wednesday, June 25, 2014 11:55 PM