Planning Frequency

Planning frequency is the time between material plan recalculations. The Material Plan must be completely updated when the demands change.

Two questions must be answered before determining whether the material plan needs to be recalculated.

Some examples of factors that influence the decision are:

Methods for recalculation of material plan

There are three main methods to recalculate the material plan:

Batch net change

When batch net change is used, the material plan is recalculated if a transaction has or will affect an item’s material plan.

Recalculation is based on the affected transaction and is done separately in 'Material Plan. Re-create' (MMS999).


Recalculation is part of 'Night Run. Start' (CRS999) and is performed automatically. It can also be started manually from the AUX menu.

The automatic run is performed for the items that have qualified to be part of the net change run. To qualify for the net change run, items transactions or planning data must have been changed since the last run. M3 keeps track of all items that have qualified for the net change run in a separate file.

The file contains information about when and why an item is planned for recalculation.

If the activity is already complete, the current date is used as the recalculation date. When 'Material Plan. Re-create' (MMS999) is run, the lines handled will be those whose recalculation dates have already passed or are the same as the current date.

Reasons for net change

Below are different reasons to run a net change:

Note that all changes that affect the material plan do not require a net change. Certain changes require regenerative net changes. See also Regenerative Net Change below.

Optimally, the night run should be started late enough (after midnight) so that the date has already changed by the time 'Material Plan. Re-create' (MMS999) is run. Otherwise, 'Material Plan. Re-create' (MMS999) must be started manually, so that proposed action messages are displayed in a timely manner.

Material requirements planned items are calculated in low-level order. This parameter is set in the 'Planning method' field on 'Item. Connect Warehouse' (MMS002/E). Low-level codes are automatically calculated and updated on product structure changes and acquisition settings in (MMS002). 'Item per Warehouse. Analyze and Repair' (MWS980) can be used to find and repair errors in low-level codes. In case a full low-level code re-set and recalculation are needed, 'Product. Re-create Lowest Levels' (PDS910) can be used. It is not advised to use this program frequently, as it can run for a long time and must finish before material plan recalculation can be performed again.

Continuous net change

Continuous net change implies that the material plan will be recalculated directly after a change that affects the material plan.

The changed record is placed in a process queue for records that have the current date as the recalculation date.

Continuous net change is activated in the ‘Continuous net change’ field on 'Item. Connect Warehouse' (MMS002/E).

For performance reasons, it is recommended to use this method on a few items as possible, and only where the item is fast-moving and cannot wait for the next batch recalculation.

Manual net change

Note that it is possible to request recalculation by pressing F18 in 'Material Plan. Open' (MMS080).

A setting in the parameters for 'Material Plan. Open' (MMS080) indicates whether calculation is done per level or if it will be possible to break down the product structure to several levels.

Regenerative net change

Regenerative net changes mean that material plans for items are recalculated regardless of planning method. This method should not be used on a regular basis but can be helpful to fix an incorrect planning situation.

Regenerative recalculation requires high computer capacity and takes longer time because all items in the selection are included in the calculation. This differs from batch recalculation, in which records are not placed in the process queue for all basic data changes.


Inspection time on a receiving method for purchased items is changed from three to two days. For these items’ open orders, this results in a one-day difference in the planned put-away date in the material plan.

The result of changing inspection time will be apparent when a regenerative calculation is carried out.


In 'Material Plan. Calculate Regenerative' (RPS999), a line of selections can be defined for the actual run.

Examples of selection choices:

These choices are available when using F16='Advanced Settings. These should be used with caution as they override standard MRP logic and can have a negative impact on performance:

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