Source: http://help.sap.com/saphelp_scm70/helpdata/EN/c1/147a375f0dbc7fe10000009b38f8cf/frameset.htm
You use Supply Network
Planning (SNP) to create a feasible, medium to long-term production and
distribution plan for critical products (products with long replenishment lead
times or products that are produced on bottleneck resources). This plan should
ensure that the required product quantities in your supply chain are available
at the right place, at the right time, without overloading bottleneck
resources for production and transportation. A key task of SNP involves
determining the optimum sources of supply. Based on cost aspects, SNP decides
where, when, and in which quantities products should be procured, produced, or
transported in the supply chain. SNP plans according to periods and quantity.
Order dates are exact to the day and detailed order sequences are not
considered.
You use Production Planning and Detailed Scheduling (PP/DS) for
detailed production planning; that is, for planning the lot sizes to be
procured, for planning order dates to the second, and for planning order
sequences on the production resources. Accordingly, in PP/DS you plan in-house
production based on detailed, complete BOM (production process model plans,
iPPE process structures, or PP/DS runtime objects) and on resources with a
time-continuous capacity.
For SNP planning, on the other hand, you use rough
production process model plans (PPM plans). These contain only a section of
the BOM with the critical components. You use resources with a period-related
capacity, where the smallest period is a day.
You separate the
responsibilities for planning using the PP/DS horizon and the SNP production
horizon. Planning within the PP/DS horizon is part of PP/DS planning and
planning outside of the SNP production horizon is part of SNP planning,
although the planning areas may also overlap. If, within short-term planning,
you want to execute more detailed planning on receipts created by SNP, meaning
that you want to plan them with detailed dates and a complete BOM, you must
convert the SNP receipts into
PP/DS receipts. If the SNP receipts reach the PP/DS horizon, you
convert the SNP receipts into PP/DS receipts.
SNP
planning results primarily in stock transport orders. These orders are
relevant to PP/DS if the stock transfer requirements concern production
plants.
SNP
alone plans receipts and determines cost-effective sources of supply and lot
sizes. You only use PP/DS to plan the receipts created by SNP in detail (that
is, to complete the BOM) and to execute sequencing (for example, with setup
time optimization). PP/DS copies the SNP source of supply decisions during
conversion.
Horizon
If you want the PP/DS horizon and the SNP planning
period to always follow each other without a gap, you only enter the SNP
production horizon in the location product master, and no PP/DS
horizon. The system automatically
uses the SNP production horizon as the PP/DS horizon. This is required in particular if you define the
SNP production horizon in calendar weeks or calendar months.
Resource
If you want to
consider the resource loads caused by PP/DS orders in SNP planning, and adjust
the SNP planning accordingly, you must use mixed resources (single-mixed
resources or multimixed resources)
Source of Supply
Use a PP/DS PPM, for which you have defined a lot
size interval, to create a corresponding SNP PPM with the same lot-size
interval.
Use a PP/DS PPM, which allows operations to be
processed in different modes, to create an SNP PPM for each possible mode
combination.
If you want SNP to
specify the sources of supply during conversion, and you are planning with an
automatically generated SNP PPM, the system automatically uses the basic PP/DS
PPM.
Define the
lot-size interval of a PP/DS PPM, for example, based on the process-related or
technical creation restrictions. Use the PP/DS minimum lot size as the SNP
minimum lot size. As maximum lot size, specify in the SNP PPM the total
quantity that can be produced in one day.
