Buffers

A buffer is in (logical of physical) inventory point for a item at a certain location.

Different types of buffers exist:

  • Default:
    The default buffer uses an “producing” operation to replenish it with additional material.
  • Infinite:
    An infinite buffer is unconstrained and has an infinite supply of the material.
    Propagation through a bill of material will be stopped at an infinite buffer.

Fields

Field Type Description
name non-empty string
Unique name of the buffer.
This is the key field and a required attribute.
You have to use the convention of using “item @ location” as the buffer name.
item item
Item being stored in the buffer.
This is a required field.
location location
Location of the buffer.
This is a required field.
The working hours and holidays for the buffer are taken from the ‘available’ calendar of the location.
description string Free format description.
category string Free format category.
subcategory string
Free format subcategory.
If this field is set to ‘tool’, the field ‘tool’ will automatically be set to true.
onhand double
Inventory level at the start of the time horizon.
Default is 0.
minimum double
Desired minimum inventory, aka safety stock.
Use this field if the safety stock doesn’t change over time.
The solver treats this as a soft constraint, ie it tries to meet this inventory level but will go below the minimum level if required to meet the demand.
A problem is reported when the inventory drops below this level.The safety stock target is expressed as a quantity. If you want to define a safety stock target as a time value (aka days of inventory), you can set a post-operation timeon the producing operation of the buffer.
minimum_calendar calendar
Refers to a calendar storing the desired minimum inventory level, aka safety stock.
Use this field when the minimum inventory level is varying over time. Otherwise use the minimum field. If both fields are specified, the minimum field is ignored.
maximum double
Refers to a calendar storing the maximum inventory level.
This field is not used by the solver.
A problem is reported when the inventory level is higher than this limit.
maximum_calendar calendar
Refers to a calendar storing the maximum inventory level.
Use this field when the maximum inventory level is varying over time. Otherwise use the maximum field. If both fields are specified, the maximum field is ignored.
mininterval duration
Replenishment batching window.
When multiple replenishments for the buffer are planned closer than the time window specified in this field, the solver algorithm will try to combine them into a single larger replenishment.
The default value of the batching window is -1, which keeps the batching logic deactivated.
producing operation
This operation will be instantiated by the solver to replenish the buffer with additional material.
You can specify this operation explicitly.
Or, you can leave this field blank and let the system automatically create an operation. The generated operation is using the ItemSupplier and ItemDistribution models as input.
In versions before 3.0 the only way was the explicit construction of the operation to populate this field. From version 3.0 onwards we recommend to use the auto-generated operations, unless you have some very specific modeling requirements.
From version 4.0 onwards, this field is deprecated. It is left only for backwards compatibility. New implementations and upgraded installs should use the easier modeling constructs itemsupplier, itemdistribution and operation.
flows list of flow Defines material flows consuming from or producing into this buffer.
flowplans list of flowplan
This field is populated during an export with the plan results for this buffer. It shows the complete inventory profile.
The field is export-only.
The description of the flowplan model is included in the section on operationplan.
tool boolean
A flag to mark buffers that are actually representing a tool.
Default is false.
The impact on the planning results is visible in the pegging and criticality calculations.
level integer
Indication of how upstream/downstream this entity is situated in the supply chain.
Lower numbers indicate the entity is close to the end item, while a high number will be shown for components nested deep in a bill of material.
The field is export-only.
cluster integer
The network of entities can be partitioned in completely independent parts. This field gives the index for the partition this entity belongs to.
The field is export-only.
hidden boolean Marks entities that are considered hidden and are normally not shown to the end user.