Project System - Scheduling

[ladislavpl]

Hello, I have a question about scheduling in SAP Project in CJ20N.

Structure is: Project Definition – WBS Element (lvl 1) – WBS Element (lvl2) – Network (assigned to lvl2 WBS) – 5x activity

Bottom up, Backward scheduling, finish-start, last activity has constrain „finish not later“. Each activity has 1 DAY normal duration.

After scheduling, which is ok, dates are not ok. They are scheduled from earliest date 10 days (+weekends). There is not difference between earliest and latest start/finish.

Any suggestions please? What to check?

Thank you in advance for your suggestions.

[MarcioBlos]

Hi ladislavpl

When scheduling dates from a network, SAP uses the start and finish dates maintained in the network. It uses the finish date for backward scheduling and the start date for forward scheduling. Therefore, make sure to adjust the network’s start and finish dates before running the scheduling process.

Regards
Marcio Blos

[Ken_Melching]

First thing, what relationships have you defined between the Network Activities?

Check the Network graphic to see the Critical Path.  The definition of Critical Path is the float is 0 on an Activity so the Early and Lates Dates are the same.

You need to look at PS Scheduling from 2 viewpoints, WBS Dates and Network Activity Dates.  SAP has almost too much functionality with regards to scheduling.  Since you are using Network Activities then WBS scheduling just follows along with the Network Activity dates.

In your configuration for WBS scheduling make sure you have set "Network Determines Dates" and I use Strict Bottom Up Scheduling.  This makes sure the WBS dates are aligned with the NWA dates.  and subsequently the Project Definition Dates will be determined by the roll up of the WBS Dates which are coming from the NWAs.

With regards to NWA scheduling if you do not have an absolute constraint on a NWA (Must Finish On or Must Start On) then the dates you enter on the Network HEADER determine the starting point for schedule calculation.  It will use either your Start or Finish Date depending on what scheduling you set, either Forward of Backward.  SAP always performs a forward and backward schedule calculation it starts with the direction you specify.

Also look into your NWA scheduling parameters and see if you allow scheduling into the past and by how many days.  I usually set this to the maximum 999 days.

All of these settings come into play when calculating the dates.

[Lakshmipathi]

You mentioned “Finish Not Later Than” — this constraint can override backward scheduling logic. If the constraint is set as a hard constraint, SAP may schedule all activities to start as early as possible to ensure compliance. Try changing it to a soft constraint or test without it to see if dates adjust.

Ensure the network header is set to backward scheduling. In CJ20N, go to the network → Dates tab → check “Scheduling Type.” If it’s set to forward or not defined, SAP will default to earliest dates.

Check the work calendar assigned to the network and activities. If the calendar includes weekends as working days, SAP will schedule continuously. Use SCAL to verify calendar settings.

Run CJ24N or CN24 to trigger overall network scheduling. This recalculates earliest and latest dates based on constraints and relationships.