Backward scheduling in sales order

Question

Hi all,
I have 2 routes maintained which should be determined by different shipping conditions.  Let's name them as Route A with transit time 4 days and Route B with transit time 2 days.
When creating sales order, the backward scheduling takes place.  To my understanding, in case the material available date is calculated as in the past, forward scheduling will take place.
My question is - I have 2 routes with different transit time.  Is it possible to make the backward scheduling checking all available routes (in my case, ignoring the shipping condition) before start the forward scheduling?
Thanks in advance.
Cheers, Kenneth

Answer 1

This is how the system works:
the route is determines in FM SD_ROUTE_DETERMINATION. this is reached via the following call stack:
SAPL0VRF FUNCTION SD_ROUTE_DETERMINATION
SAPFV45P FORM VBAP-ROUTE_ERMITTELN
SAPFV45P FORM VBAP-VSTEL_ERMITTELN
SAPFV45P FORM VBAP_FUELLEN
SAPMV45A MODULE (PAI) VBAP_FUELLEN
As you know, shipping conditions are used as a criteria to find a route.
So lets say:
Shipping Conditions A (Air) ---> Route 1 will be determined
Shipping Conditions T (Truck) ---> Route 2 will be determined
Route 2 gets determined. Later, Function SD_SCHEDULING will be called. The following call stack reflects this:
SAPLV03C FUNCTION SD_SCHEDULING
SAPFV45V FORM VERSANDTERMINIERUNG_NEU
SAPFV45V FORM MVERF_AUFBAUEN_WMENG
SAPFV45V FORM MVERF_AUFBAUEN
SAPFV45V FORM VERFUEGBARKEIT_PRUEFEN
SAPFV45V FORM BESTAND_BEDARF_ABGLEICHEN
SAPFV45P FORM VBAP_BEARBEITEN_ENDE_VERFUEGB
SAPFV45P FORM VBAP_BEARBEITEN_ENDE
SAPMV45A MODULE (PAI) VBAP_BEARBEITEN_ENDE
The call of function SD_SCHEDULING looks like this:
call function 'SD_SCHEDULING'
   EXPORTING
     if_schedule_direction   = v03c_backwards
     if_schedule_shipping    = us_vstrm
     if_schedule_transport   = us_trtrm
     if_shipping_point       = us_vstel
     if_weight_group         = us_grulg
     if_loading_group        = us_ladgr
     if_transport_route      = us_route  <<<<<<<<<<<<<<<
us_route contains the route that is determined in FM SD_ROUTE_DETERMINATION.
So only 1 route will be passed to SD_SCHEDULING. In this example, use_route = "2" (Route 2).
My understanding of your issue is that you may have a requested delivery date = 10th April (for example)
10th - 4 days = 6th, a date in the past so system must do a forwards scheduling, and then we inevitably have a later confirmed delivery date. However, before you have the system do a forwards scheduling, you want the system to see if the requested delivery date of April 10th can
be reached with route 1.
10th - 2 days = 8th, so there is no need to execute the forwards scheduling as the customers requested delivery date can be met
It sounds like a reasonable request to me (Route 2 could be cheaper and meet customer's delivery date but if it cant be reached, then use route 1 as you will get goods to customer on time even if it is more expensive), but I do not think it is easily achieveable. The ECC system is just not as clever as that. Maybe the APO scheduling offers some more flexibility regarding this? The ECC system simply uses the route (i.e. transit time of route) as part of the initial backwards scheduling. If dates in the past, it will switch to forwards scheduling.
There is no method by which it will not switch to forwards scheduling if there is another route available. It cannot do this because as far as FM SD_SCHEDULING is concerned, there is only 1 relevant route.
I am not even sure if this is possible via a user exit. The problem is preventing the forwards scheduling in the case of route 2 resulting in past dates. There is definitely no user exit to do this within SD_SCHEDULING. And then there is the possibility of route 1 determining past dates. In the case of both routes determining past dates, which route should be used. So I do not think there is any possibility to so this from within the scheduling function.
Maybe you could implement your own "rough" scheduling logic in EXIT_SAPL0VRF_001. This exit is called in FM SD_ROUTE_DETERMINATION and allows you to determine your own route. And then this route will later be passed to the standard scheduling function. This would be a fairly significant development effort though.