Incorrect Scheduling (CJ20N) vs. correct network scheduling CN24 (without WBS scheduling)

[Serge_Driendl]

Hello all,

as my post is quite long: thanks in advance for the help!

I currently have a small scheduling problem in PS (S/4 1909): I have a scheduled project in which the activity duration is shortened for an activity lying in the middle of the schedule. Here, the subsequent scheduling at ProjDef level in CJ20N spits out wrong results for me:

1. apparently no overall network scheduling was carried out or the WBS elements do not get the dates of the networks or have an undesired restrictive effect.

2. overall network scheduling via CN24 schedules correctly (see case study below), but is not useful for the project because WBS dates are not updated.

3. CJ20N should actually do overall network scheduling across networks and WBS / so I'm having a hard time finding the error.

I verified the "wrong" result in another system with the same result, unfortunately.

Here is my configuration, below that will be an example:

Network scheduling parameters

WBS scheduling parameters

And the example:

correctly scheduled project:

Change to an activity + scheduling Activity shortened from 10 to 2 days

--> Rescheduling moves the network activity back, but does not move the first network towards the changed activity.

--> WBS elements should on the one hand accept the dates of the network and on the other hand not have a restrictive effect.

Scheduling via CN24:

- Project networks are scheduled correctly, however dates are not passed to WBS elements.

- What I see but don't understand: there seems to be no overall network scheduling in CJ20N

[Ken_Melching · Accepted solution]

Run CN24 or CN24N to get the networks, then run CJ29 to get the WBS.

Throw them together in a periodic batch job to keep the dates correct.

Then create a custom transaction to run them back to back with a Project Definition Input.

[Serge_Driendl · Accepted solution]

thx again for you feedback!.

[Ken_Melching]

So SAP offers 2 scheduling options (WBS Scheduling and Network Scheduling) because sometimes projects are only WBS elements. When you use networks they need to be the primary scheduling objects and the WBS gets its dates from the assigned network activities.

Your configuration settings look correct for this scenario.

To make this work you need to run scheduling twice.

1. Run Network scheduling. In Proj Builder select the network header, Edit, Dates, Schedule, save. This carries out network scheduling. If you have multiple network headers use Overall network scheduling. Now watch out for the NW header dates if you don't have constraints.

2. Run WBS Scheduling. In Proj Builder select the project definition, edit dates, schedule, save. This will update the WBS dates froom the new network dates.

[Serge_Driendl]

Thx Ken!

So you mean that for a project with several networks/WBS I have to:

1. CN24: schedule networks
2. CJ20N: schedule project

That would mean that the scheduling takes a lot longer than I thought it would take... There is really no other option?

Whats makes me wonder is, that the scheduling function in the CJ20N should do exactly those 2 steps, as I customized the system this way. A strict bottom up scheduling just makes no sense if it doesnt calculate the network activity dates first and then passes them to the WBS...