Understanding the Plan Generation Process

After you run the Load Planning Instance process (PL_LOAD_OPT) to define the planning model, you can generate a plan using the Initiate Solver component for the solver that you want to use. You can rerun any of the solvers after you have made manual changes to the plan using the Material Workbench or Capacity Workbench.

Before you generate a supply plan, ensure that you have a planning instance defined and loaded into a planning engine that you use to create the plan. Generating the plan can be an iterative process. You can run a plan multiple times to create a higher-quality plan. When you initially define the model, PeopleSoft Supply Planning passes the data that you identify as part of the planning process to the planning engine using the Load Planning Instance process. If the data is incomplete (for example, if the forecast numbers are inaccurate or if a time fence is set up improperly), stop the generation process and use the transaction system to correct incomplete or incorrect data. You can change plan data using the planning engine; however, only planned orders, order cancellations, and date changes are transferred back to the PeopleSoft transaction system.

Solvers

When you generate a material plan in PeopleSoft Supply Planning, you choose from a series of solvers. Solvers are flexible tools that analyze data and attempt to find feasible plans (based on the business planning needs) that contain no material shortages or capacity violations. Material feasibility indicates that the longest cumulative lead time exists within a manageable time frame in which no material shortages exist. Capacity feasibility indicates that no critical capacity violations exist for aggregate resources that are marked for repair in the planning time period. In addition to producing material and capacity feasible plans, solvers identify and report unavoidable instances in which the plan is jeopardized, for example, when material cannot be sourced or when insufficient lead time is available to satisfy a demand.

Using solvers, you first produce a plan based on existing supply and demand for an item to arrive at a feasible material and capacity plan. Then you manually repair infeasibilities and run more comprehensive solvers to create a plan that is ready to use when it is generated.

Time Fences

PeopleSoft Supply Planning uses fences to place boundaries on the magnitude of the planning problem, to restrict the behavior of the solvers during certain time periods, and to automate certain conditions at certain times. Solvers use fences to determine how far supply or demand tasks can be moved forward or backward to meet planning needs. You can use time fences to help determine how solvers analyze supply and demand.

Use these time fences when running PeopleSoft Supply Planning solvers:

Term	Definition
Start of Time	Represents the beginning time boundary for the planning instance. PeopleSoft Supply Planning solvers do not recognize orders or changes before this date. Used with the end of time, the region defines the time period within which the system recognizes orders and changes. The start of time must be equal to or prior to the current date time.
Early Fence	Represents the beginning time of the interval within which solvers process the elements of the material and capacity feasible plans. The early fence must be greater than or equal to the current time and less than the end of time. Usually, you set the early fence to the current date. Both a global early fence value (for the entire planning instance) and an item-specific early fence value exist. Prior to the early fence, solvers cannot: Create any new supply with a start time before the early fence. Reschedule current tasks that have a start time before the early fence. Reschedule existing tasks starting after the early fence to start before the early fence. Cancel current tasks that have a start time before the early fence. Note: The early fence provides a boundary before which solvers cannot move tasks. As a general rule, the region before the early fence is frozen to the planning solvers.
Current Time	Represents the current date and time. Each planning instance has a base date and time that is equal to the current date and time to which all of the other fences and horizons are specified as offsets. Current date and time is unrelated to the actual (or system date time), except when you use the actual date and time as a default for specifying the current date and time.
Capacity Fence	Represents the date and time that solvers begin ignoring capacity violations. After this date, the Feasible solver ignores violations. In plan analysis, solvers do not report or include any capacity type exceptions that occur after the capacity fence. The capacity fence must have a value between current time and the end of time. If you define the capacity fence as current time, the solvers ignore all of the capacity violations. The capacity fence default value is the end of time.
Late Fence	Use the late fence as a reporting fence only. Exceptions that occur after the late fence are not included in any metric when analyzing plan quality. The late fence must be greater than the early fence and equal to or prior to the end of time. The late fence default value is end of time. Note: All solvers net supply and demand and create new supplies through the end of time.
End of Time	Represents the concluding time boundary. PeopleSoft Supply Planning solvers do not recognize orders or changes after this date. The end of time must be at or after the current date and time.

Planning Conditions and Time Fences

Each solver processes planning conditions in conjunction with time fences. You also maintain tasks within time fences. This table lists how PeopleSoft Supply Planning solvers address planning conditions. The last column indicates whether manual rescheduling is available for the corresponding condition:

Planning Conditions	Material Solver	Feasible Solver	Manual Rescheduling
Reschedule tasks before early fence.	No	No	Yes
Move orders before early fence.	No	No	Yes
Create new orders before early fence.	No	No	NA
Respect late fence.	No	No	No
Recognize violations before early fence.	NA	No	NA
Respect capacity fence.	NA	Yes	No
Beginning fence and ending fence boundaries.	Early fence and end of time	Early fence and end of time	Start of time and end of time

Time Buckets

Capacity plans are created in bucket sizes that are associated with each aggregate resource. Material plans that are generated by the Material solver and Feasible solver are based on time-phased netting of demands and supplies.

Item Substitution

You can predefine valid alternatives for an item when that item (the item that is used as a component in a production order) is unavailable. When using substitute items with PeopleSoft Manufacturing, PeopleSoft Supply Planning automatically suggests the substitute item when the original is in short supply or is unavailable.

You can define substitutes for an item on the Item Definition and Item Attributes by Unit pages and use them as defaults when maintaining components on a bill of material (BOM). When defining substitutes, you can specify effectivity dates and conversion factors. The conversion factor defines how many of the substitute is required to replace the original item. You can set a priority by which the substitute item with the highest priority (the substitute with the lowest priority number) is substituted first in PeopleSoft Supply Planning.

You can define general substitution options for each manufacturing business unit when you establish business unit group definitions in PeopleSoft Supply Planning.

Additionally, to enable the solvers to substitute for items, select the Allow Item Substitution option on the Initiate Feasible Solver page. When the projected quantity on hand of the primary item cannot meet the demand, the Feasible Solver can use substitutions when creating new planned production, if these criteria are met:

You selected the Allow Item Substitution option on the business unit group definition.
You selected options for allowing substitutions during the running of the corresponding solver.
No partially completed operations exist for the item.
Items have not been issued for the operation.
Item Substitution is not frozen for the order.
You can select the Frozen option for substitutions on the Refine Plan component for planned production orders and scheduled production orders. The mass maintenance utility also allows for component substitutions to be frozen. When a production ID or production schedule is marked as being frozen for substitutes, no substitution will be performed.

Solvers use substitutions for dependent demand only. They do not use substitutions for end items, such as sales orders, transfers, or forecasts. Solvers consider substitute items (all of the items that are effective for the period considered) according to the order of their priority.

Note: PeopleSoft Supply Planning assigns higher low-level codes to substitute items than to primary items. This ensures that primary items are planned before substitute items.

The substitute item projected quantity on hand must meet the total demand of the substitute item quantity that is needed for each primary item multiplied by the conversion factor. The solvers do not use partial substitutions. If the solvers cannot meet this demand with substitutions, they plan supply for the primary item.

Note: PeopleSoft Supply Planning solvers use valid substitutions only. However, PeopleSoft Supply Planning does not validate substitutions that are made within the transaction system and loaded into the planning instance tables.

Note: The Material solver performs substitutions only when a component is beyond its phase-out date and dependent demand exists for the component.

Production End Dates

Solvers determine the start and end dates for production by forward scheduling from the start date or backward scheduling from the due date. In most circumstances, solvers use backward scheduling; however, if not enough lead time is available for materials, or if no capacity is available and the order might be delayed, solvers use forward scheduling to find the earliest availability date for the production outputs. If a work center calendar exists for an operation, solvers validate the operation start and end dates against this calendar. If the work center calendar does not exist for an operation, PeopleSoft Supply Planning uses the business unit calendar for operation date validation.

To calculate start and end dates for production, solvers use this information:

Operation start and operation end quantity.
Component quantity based on the operation start quantity.
Output quantity based on the operation end quantity.
Effectivity dates for the components.
Substitutions for the components.
Offset lead time for send ahead and intransit.
Load start offset (the duration between the operation start time and the net start time).

Solvers calculate this number for existing production IDs.

In addition to the production start and end times, the scheduling algorithms provide the solvers with this information:

Operation start and end time.
Components (their required quantity and any substitutions, if checking for material capacity).

For existing production IDs and for planned production, solvers validate the operation dates against the work center or business unit calendar only.