Definition: Rounding residuals are virtual quantity differences that occur when quantities are rounded to different degrees of precision, mostly when the EWM communicates with S/4 system. These quantity differences don’t physically exist in a warehouse; they are only found in the system. SAP has named these non existent residual quantity at bin level as ‘‘Decimal Dust”

Decimal dusts are primarily created when Buom to Auom results in large decimal conversion like KG to LB conversion( Imperial UOM conversion). Conversion between two units of measure using a conversion factor that contains more than three decimal places (for example, 1 lb ~ 0.453592 kg).

Creation of Decimal Dust in system:

Create a  product with base unit of measure KG and alternative unit of measure LB. The conversion is 1 LB ≈ 0.453592 KG

Post GR of 1 LB first and next 2 GR next to create dust in system

/SCWM/ERP_STOCKCHECK has been enhanced to store dust value and it results in Decimal Dust which is physically non existent in EWM Storage Bin.

The result is a difference of approximately 0.0004 kg between EWM and Inventory for the same conversion.

This small difference of approximately 0.0004 kg is considered a rounding residual and must be handled accordingly in Warehouse Management to avoid further issues. If the rounding residual isn’t handled correctly, the following symptoms could occur in a warehouse.

• Hanging update queues while processing goods movements

• Errors while creating and confirming warehouse tasks

• Small leftover quantities on storage bins or handling units that can’t be removed and that block the bins or handling units

• Stock inconsistencies between Warehouse Management and Inventory

Solution: SAP has come with latest note 3138922 – Rounding Residuals (aka. “Decimal Dust”) – Consulting Note which is applicable from 1709 to higher version.

Recently for a customer we implemented this note in 1909 version. For blog readers, please carefully go with details of note main Note. Our customer had already Pilot note(4. Substitution of Pilot Note 2428689 (“Decimal Dust”) implemented which we had to de-implement and implement the superior note.

How rounding residual Works:

Rounding residuals can only be posted to the S/4 system (manually or automatically) if the absolute cumulative quantity exceeds a threshold of 0.0005, as measured in the base unit of measure. All rounding residuals in the difference analyzer are collected and added together based on the following stock attributes:

• Product
• Batch
• Party Entitled to Dispose
• Owner
• Stock Category
• Stock Usage
• Special Stock Attributes (Document Category, Document Number, Item Number)

With the note implementation, below customizing entry is created which allows intelligent way to clearing rounding residual.

Note–> For posting residual to S/4 system, dust  should always be a greater threshold of 0.0005. As S4 uses precision of 3 decimal places only, any dust created and recorded in system( EPR stock checks or Diff analyzer) below than 0.0005 will not be posted to S/4

In EWM we will always calculate and correct quantities with a precision of 14 decimal places. However, S/4 systems only support 3 decimal places so we can only correct on the first three decimal places.

Let’s say you have collected a rounding residual of 0.000567 in EWM and post it from the difference analyzer to the S4 system. This rounding residual will be rounded to 0.001 when using a precision of 3 decimal places. So in the S4 system we will correct 0.001. However in EWM we will keep track of all 14 decimal places and create a new rounding residual of 0.001 – 0.000567 = 0.000433. We don’t loose any precision due to postings to S4, we will still keep track accordingly

SAP has introduced 3 ways of posting Decimal Dust.

1. Manual Removal from Difference Analyzer
2. Automatic Removal at Posting of New Rounding Residuals
3. Automatic Removal Using Batch Job

Please read SAP note 3138922 – Rounding Residuals (aka. “Decimal Dust”) – Consulting Note very carefully to choose the correct approach. For our customer, we have enabled Auto posting of decimal dust via configuration.

Since, in our example, posting GR of 3 LB, created a dust of 0.00048< 0.0005( Threshold), no posting will happen.

Lets post another GR of 1 LB

Rounding residual is still< 0.0005, lets post more GR to increase the threshold.

Lets post more GR and see how system post the dust. The moment residual dust accumulation is >0.0005,  posting is performed in S/4 with 3 decimal of precision. In below example, 0.001 and 0.002 KG has been posted via automatic rounding residual activation in configuration.

In EWM, system will always keep the record of dust lower the 0.0005 and wait for the amount to be increased via inventory related transaction.

Its also possible to record ‘Reason Code’ in S/4 against which decimal dust has been posted. Customers have to implement the note-3218692 – Rounding Residuals: Reason Code in Material Document. There are many notes which are mandatory to be implemented based on version of S/4 HANA system. All the notes are mentioned in main note 3218692.

Thanks for reading. All tests have been performed in S/4 HANA 2022 Sandbox system.