Scheduling in Microsoft Project and the Project System (SAP-Bibliothek

Scheduling in Microsoft Project and the Project System

Use

Scheduling in Microsoft Project and the R/3 Project System differs in detail. This can cause unexpected results when transferring data between the two programs.

Features

Scheduling in Microsoft Project

In Microsoft Project scheduling is only in one direction. You decide when you create a project whether the system should schedule from the project start date or the project finish date. If you choose scheduling from the start, all tasks are initially scheduled to start as soon as possible. If you schedule from the finish, all tasks are scheduled to start as late as possible.

Constraints

You can add constraints to a task in Microsoft Project either manually or automatically.

Manual constraints

To add manually, call up the detail screen for the task. Go to the Advanced tab page

In the Constraint Task section, enter the type of constraint and the date. The following types of constraint are available in Microsoft Project:

Start no earlier than
Start no later than
Finish no earlier than
Finish no later than
Must start on
Must finish on
As late as possible
As soon as possible

The last two options are not strictly constraints. Depending on whether you are scheduling from the start or the finish, the default value is either As soon as possible or As late as possible. If, for example, you change the value from As soon as possible to As late as possible the task is scheduled to finish as late as possible within the period of the summary task. In this case successor tasks are taken into account.

This is one way of moving dates in OpenPS from earliest set of dates to latest or vice-versa.

Choose OK.

Automatic Constraints

If you move a task by dragging it in the diagram area or by entering a date, Microsoft Project automatically sets a constraint for the task. If the project is scheduled from the start, it sets a Start no earlier than constraint. If the project is scheduled from the finish, the system sets a Finish no later than constraint.

Duration, Work, and Resources

Work and duration are defined in Microsoft Project as in the R/3 Project System. Work is the amount of effort, measured in time units, put into a task by a resource. The duration is amount of time between the start and finish of the task. Resources are the people, equipment, office space etc. for carrying out a task. On the Resource sheet, you define the resource (see Entering Resources in Mapping Microsoft Project Objects to the R/3 Project System) specifying how many units are available at this resource.

In Microsoft Project duration, work, and resources are mutually dependent:

Duration = Work/Resources

On the Advanced tab page you specify which of these three parameters is to be kept constant in the Task type field. The program uses the settings from the calendar and other options to convert units

You have created a task that has a duration of 10 days and assigned a resource to this task with one unit. In the project options you have specified a 5 day week with an 8 hour working day. The system then calculates the work to be 80 hrs. If you then change the duration to 12 days, the following happens:

If the task has a fixed duration, the work increases to 96 hrs (12x8), and the resources remain at one unit.
If the task has fixed work, the work remains at 80 hrs but only 0.83 units resources are required.
If the task has fixed units, the units required remain one and the work increases to 96 hrs

Since the number of resources is not transferred to the Project System, use tasks with fixed work if you want to change the duration and with fixed duration if you want to change the work.

Scheduling in the R/3 Project System

In the Project System networks and projects are always scheduled forwards and backwards. The differences between the various scheduling types are the date from which the system starts scheduling and the direction in which it schedules first.

In forward scheduling the system:

starts at the basic start date and schedules forwards
determines the earliest activity dates
determines the scheduled finish date
schedules backwards
determines the latest activity dates
determines the latest start date

Similarly in backward scheduling the system:

starts at the basic finish date and schedules backwards
determines the latest activity dates
determines the scheduled start date
schedules forwards
determines the earliest activity dates
determines the earliest finish date

This means that in the Project System there are always two sets of dates for an activity, the earliest and the latest.

How the dates of the WBS elements are determined and how these dates are passed on in the hierarchy depends on the system settings.

For more details on scheduling, see Dates (Component PS-DAT) in the SAP Library.

Transfer of dates to/from Microsoft Project

If a project that has been scheduled in the Project System is transferred to Microsoft Project the earliest dates are used, if you choose Schedule project from start in the OpenPS wizard; the latest dates are used, if you choose Schedule project from finish.

Constraints

If a task with a constraint is transferred to the R/3 Project System, the same type of constraint is set in PS as in Microsoft Project. That means for example, if a start constraint is set in Microsoft Project a start constraint is also set in the R/3 Project System. This also applies to constraints that are set automatically by Microsoft Project (see Automatic Constraints above).