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Back scheduling

Hello all,

"If backward scheduling determines a material-availability date or transportation plang. date that lies in the past, the system automatically carries out forward scheduling to determine a delivery date that can be confirmed." What does this statement means? Kindly explain what does "date lying in the past" means? Plz give example of past date.


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4 Answers

  • Best Answer
    Posted on Jan 21, 2009 at 07:12 AM


    For example you are creating a sales order today 21.01.2009 and the requested delivery date is 30.01.2009 from the customer side

    Transit time is 2 Days

    Transportaion planning time is 2 days

    Loading time is 1 day

    Pick/pack time is 1 day

    Consider these settings

    Now backward calculation

    30.01.2009 (requested delivery date)-2 days (transit days)-1 day(loading time)-2 days (transportation planning time) = that is on 25.01.2009 there should be enough stocks in the unrestricted stocks and system checks stocks for this day or date ,that is 25.01.2009,whether the stock is available enough

    This date 25.01.2009 becomes the material available date

    Note Transportaion planning time and Pick/pack time will run parallely and the higest of these two is considered for delivery scheduling so in our case Transportaion planning time is 2 days that is the highest and hence it is taken for calculation and not pick /pack time

    If the system finds enough stocks on 25.01.2009 that is material available date then it confirms schedule lines for that order this is backward

    Same example order is registered today 21.01.2009 and if the customer wants stocks on 23.01.2009

    This means 23.01.2009-2 days (transit days)-1 day(loading time)-2 days (transportation planning time) = 18.01.2009

    The order registered date is 21.01.2009 and the material availablity date is past 18.01.2009 or material available date goes to past.

    This is illogical

    This means backward is failing here and now forward calculation takes place

    This is what you have asked in your qn

    Forward calculation

    If you have enough stocks today 21.01.20092 days transportation planning time1 day loading time+2 days transit time=26.01.2009

    This means that is on 26.01.2009 the stocks can be confirmed for this order as againt a requested delivery date of 23.01.2009

    In forward the system will give 2 schedule lines first that is requested delivery date that is 23.01.2009 (in our case) with ZERO qty and the second date as 26.01.2009 with full qty

    In backward you will find only one date in the schedule lines which is the same as requeted delivery date that is 30.01.2009 in our case

    Hope i made things little bit clear to you



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    • Hi

      Loading time and pick pack time comes from your shipping point and it is maintained as no of days as far my knowledge goes

      Transit time and transportation planning time is taken from route

      T code 0VTC(zero VTC) provided if you have route determination in your sales order otherwise it is taken as Zero days

      In img-enterprise structuredefinition-logistics execution-----shipping pt

      Here you choose your shipping pt and click on the details(blue lens on top)

      Here you will give loading time and pick/pack time

      Here determine load time and pick/pack time give as C for your shipping pt

      The moment you choose the key as C an extra tab will open which you can specify the no of days

      The loading time is defined as no of days like that and it is taken from shipping pt for delivery scheduling

      Also check in t code OVLZ

      Img-logistics executionshipping-basic shipping functions-scheduling--define scheduling by shipping pt

      Go to Zero VTC tode you will find this transit and transportation lead times there

      In my practical experience these lead times are maintained in no of days and they are used for delivery scheduling eventhough SAP has given the option to define these in no of hrs for very precise delivery scheduling but the same is not practised much

      Hope this clarifies your doubt



  • Posted on Jan 21, 2009 at 07:00 AM

    Go through this thread which will answer your question

    [material availability date |material availability date;


    G. Lakshmipathi

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  • author's profile photo Former Member
    Former Member
    Posted on Jan 21, 2009 at 07:01 AM

    Take this example:

    Today's date: 7th

    C/s requested date : 10th

    Transit time: 2 days

    Loading time: 1 day

    Pick/Pack time: 1 day

    Now it is true that you have enough stocks what the c/s is asking for but consider this back calculation:

    To deliver the goods on 10th, the goods should leave plant on 8th since 2 days is the transit time.

    For the goods to leave the plant on 8th, we have to start loading the vehicle on 7th since 1 day is the loading time.

    To start loading the truck on 7th, we have to start packing the material on 6th since 1 day is the Pick/pack time.

    So goods should be available on 6th.

    BUT TODAY IS this is what is meant by 'lying in the past'

    So now the system does forward scheduling.

    Hope this helps

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  • author's profile photo Former Member
    Former Member
    Posted on Jan 21, 2009 at 07:20 AM

    Hi Shidhant

    Sytem always atarts with backward scheduling first.

    In Backward scheduling,system takes the "Requested delivery date" into consideration and calculates backward taking the lead times into consideration and ultimately calculates the "Material availability date" and the "Transportation planning date".

    If both these date are after the order date and material is also available on the material availability date, then only the Requested delivery date can be confirmed.

    Even if one of the date also is in the past that means earlier than the order date, or material is not available on the material availablity date, then the Requested delivery date can not be confirmed .

    In this case system immediately starts with Forward scheduling.

    It will be clear with this example.

    Suppose, customer has placed an order to-day(21/01/2009) and has requested to deliver the goods on dt.28/01/2009.

    Here, order date is 21/01/2009

    Requested delivery date is 28/01/2009.

    Now, system will take this Requested deliverty date (28th jan) into consideration and calculate back ward to test whether this requested date is possible to confirm or not.

    Let, the transit time is 3 days to reach the customer, that means if I will start on 25/01/2009 then only my goods will reach the customer on 28th.

    So, Goods issue date is 25/01/2009.

    Let, the Loading time is 2 days, taht means if I will start loading on 23/01/2009 then only my goods can leave for the customer on 25th.

    So, Loading date is 23/01/2009.

    Let's say,time taken for planning the transport is 1 day, that means if the Transportation planning is started on 22/01/2009,then only I can start loading on 23/01/2009 but the material also must have been picked and packed.

    So I will calculate the Material availability date from this loading date.

    Let, time required for picking and packing is 3 days, that means if I will start Picking/packing on 20/01/2009 then only loading can start on 23/01/2009.

    This Material availability date is falling in the past ( earlier then the order date) i.e, 20/01/2009.

    In this case, the requested delivery date 28/01/2009 can not be confirmed and system will go for Forward scheduling.

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