Definition of Time-Based Constraints in Interactive Planning 

Use

A number of constraints are taken into account during the SNP optimization run, including capacity constraints that have been defined for resources. You usually use the SNP optimizer profile to specify which constraints you want the optimizer to consider during the optimization run. However, in certain circumstances, it might be necessary to define constraints that are time-based; for example, if a supplier provides varying quantities of a product from bucket to bucket. You can define these time-based constraints in interactive planning. You can set the following bounds:

●      An upper bound for external procurement (at product-location level)

●      An upper bound for stock on hand (at product-location level)

●      An upper bound for production (at product-PPM/PDS level)

●      An upper bound for transportation (at product-transportation lane level)

●      An upper bound and a lower bound for total receipts (at product-location level)

Prerequisites

The following prerequisites must be met for considering time-based constraints:

●      You have not set the Ignore Time-Based Constraints indicator in the SNP optimizer profile.

●      You use a SAP GUI as of version 7.10. In this case, you can see in interactive SNP planning whether or not you have entered 0 in a key figure. This is particularly useful for the receipt upper bound.

Features

Upper Bounds for External Procurement, Stock on Hand, Production, and Transportation

●      In the data view OPT_TSBD in the standard SNP planning book 9ATSOPT, there is a table in the lower part of the screen containing the four key figures Procurement Upper Bound, Stock Upper Bound, Production Upper Bound, and Transportation Upper Bound that you can use in addition to the standard functions of interactive SNP planning. You can define upper bounds for the individual key figures in specific periods. These upper bounds are then taken into account by the system when you perform an SNP optimization run.

●      The three upper bounds for external procurement, production, and transportation are considered by the optimizer as pseudo-hard constraints. Pseudo-hard constraints can be violated but only by calculating infinitely high penalty costs, which means that the optimizer only violates this type of constraint if it cannot find any other feasible solution.

For external procurement, transportation, and production, you cannot define any time-based lower bounds because this could prevent the optimizer from finding a feasible solution.

●      In the SNP optimizer profile, you can specify whether you want the optimizer to consider the upper bounds for stock as a soft constraint or a pseudo-hard constraint (on the Extended Settings tab page, activate or deactivate the Consider Upper Bounds for Stock as a Soft Constraint indicator). The optimizer can violate soft constraints by calculating penalty costs. You can define these penalty costs in a time-based key figure in planning book 9ATSOPT.

The safety stock is the lower bound that can be defined on a time basis for stock on hand. It is always a soft constraint for the optimizer. There is another time-based key figure in planning book 9ATSOPT that you use to define penalty costs for falling below the safety stock level.

●      You can use the Display Dependent Objects function to define the upper limit for production for specific production process models (PPMs) or production data structures (PDS) and the upper limit for transportation for specific transportation lanes. You define the upper bounds for external procurement and stock on hand at location product level.

Only the relevant upper bounds are displayed on screen, based on your selection. Thus, if you choose a location product, only the upper bounds for external procurement and stock on hand are displayed.

Note that when entering the upper bound for production, you do not enter the production quantity, instead enter the number of times the PPM or the PDS concerned is to be executed. To do this, you set how often you want PPM execution to be started within a period. The duration of the PPM or the PDS then determines the period in which product quantities are available. For example, if you want to define a quantity of 30 pieces as the upper bound on the third workday and the associated PPM or PDS produces 10 pieces each time it is executed (taking 3 days), on the first workday you have to specify that you want the PPM or the PDS to be executed for a maximum of three times - and therefore enter 3 as the value for the first workday.

●      In an additional key figure for the individual upper bounds, you can show that an upper bound value of 0 is to be interpreted as an actual upper bound by specifying not equal to 0. Otherwise, a value of 0 signifies that there is no upper bound.

Upper Bound and Lower Bound for Total Receipts

In the data view OPT_TSRCBD, a table with key figures is available that you can use to define receipt upper bounds and receipt lower bounds. Both of these bounds are soft constraints for the optimizer. In two additional key figures, you can define the penalty costs for falling short of the receipt lower bound and for exceeding the receipt upper bound.

Deactivation of Consideration of Time-Based Constraints

You can specify in the SNP optimizer profile that you would like the system to ignore the time-based constraints in the optimization run (by going to the Extended Settings tab page and setting the Ignore Time-Based Constraints indicator). This can be a good idea if you want to use an SNP optimization bound profile for the optimization run, for example. If you use time-based constraints in conjunction with the bounds from the optimization bound profile, the constraints might cancel each other out. If this occurs, the optimizer will not be able to find a feasible solution.

However, if you do use the SNP optimization bound profile in conjunction with the time-based constraints, the optimizer takes into account the smaller of the upper bound values that have been defined. Note that you can also define lower bounds in the optimization bound profile. If the lower bound defined here is higher than the upper bound defined in interactive planning, the optimizer will not be able to find a feasible solution.

Mass Maintenance of Key Figures

You can also define values for key figures using mass processing. To do this, choose the function Mass Maintenance of Time Series Key Figures (on the SAP Easy Access screen, choose Advanced Planning and Optimization → Supply Network Planning → Environment → Mass Maintenance of Time Series Key Figures).

Activities

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       1.      On the SAP Easy Access screen, choose Supply Network Planning →Planning → Interactive Supply Network Planning (all Books). Choose the planning book 9ATSOPT in the planning area and the relevant data view.

       2.      Define the time-based upper and lower bounds as well as the relevant penalty costs in the planning tables.

       3.      Run the SNP optimizer in interactive Supply Network Planning or in the background. For more information, see running the optimizer from the interactive planning desktop and running the optimizer in the background.