Embedded Scheduling vs. VSS Scheduler in SAP S/4HANA Transportation Management
A while ago, we spent some time discussing the benefit of S/4HANA Basic Shipping (now referred to as simply ‘Transportation Management’) compared to LE-TRA. As LE-TRA will be decommissioned by the end of 2030, you may already be exploring the options that either the basic option of Transportation Management or Advanced Transportation Management is offering you.
As mentioned in our earlier blog article, the Basic option of SAP TM did not contain an interactive transportation cockpit. Neither does it include the possibility to select any of the TM optimizer engines, such as for example the VSR optimizer. The direct implication in basic Transportation Management is that planning is to be done manually. For example, you will have to assign individual freight units to a freight order or booking, or you can assign multiple freight units in a standard worklist (POWL) to capacity documents, but both are de facto manual procedures.
Another implication was that the VSS Scheduler wasn´t available in the Basic version of Transportation Management. This turned out to be quite inconvenient, as the scheduler arranges and sets times for activities such as unloading and loading within the requested time slots of a freight unit or freight order. Without scheduling, a user must manually adjust dates to incorporate additional time for loading and unloading when assigning freight units to a freight order, or when changing stops in the stages. This means, that on top of manual actions required to perform planning, the user also must be mindful of setting times and durations manually. Alternatively, the user can stick to the default times, which may not consider loading durations and time slots at all.
To overcome the issue of not having the optimizer engine (and consequently the VSS scheduler) available for the basic Transportation Management option, SAP is providing a new option for scheduling which has been available since S/4HANA 2020 in both basic and advanced Transportation management. This scheduling functionality is called ’Embedded Scheduling’.
It enables clients who are using the basic version of Transportation Management to schedule loading/unloading or preparation activities, whilst considering operating times of locations and/or handling resources. The standard rule-based scheduling configuration can be used for the embedded scheduler, except for scheduling constraints in customizing, which only the VSS scheduler is able to use. The main benefit delivered by the embedded scheduler is that basic Transportation Management users are now able to schedule activities where earlier these times/dates had to be set manually (or not set at all). All of this can be done with an option to consider earliness and lateness costs, which in its turn is not included in the VSS scheduler.
What is embedded scheduling?
The main goal of Embedded scheduling is to determine start and end times of a set of activities in such a way that the departure and arrival date can be accurately set for a freight order. The VSS scheduler has the same purpose, although there are slight differences in how the scheduling is executed and configured.
Embedded scheduling is using a new ABAP engine and as its name suggests, the code of this engine is written in ABAP rather than in C++, which is the code used for the VSS scheduler.
SAP emphasizes that these engines are not returning the exact same results, since these two engines are not simply a copy of one another. However, they will both try to schedule activities within the acceptable and requested time slots, considering vehicle availability and operating times.
In addition, both engines respect the travel durations which are calculated independently with the Distance and Duration Determination (DDD) function. The duration for transportation is calculated with the distance from the transportation lane and the average speed that is set for the means of transport. Both the embedded scheduling and VSS scheduling engine will plan other activities such as loading, unloading and related activities around the travel durations, as shown in a simplified way in figure 1:
How to configure embedded scheduling
From a user perspective, the configuration of embedded scheduling is very similar to the setup of the VSS scheduler. With the SAP TM 9.5 release, SAP introduced ’rule-based scheduling‘, which is now the standard option to set up rules for scheduling in S/4HANA. These rules are used by both the VSS scheduler and the embedded scheduler.
The configuration of the scheduling options is done in the scheduling settings within the planning profile. Different rules can be set for inbound and outbound operations. To select the embedded scheduler, a different strategy must be used. Instead of the VSS_DEF, the strategy VSS_EMBED should be entered as the scheduling strategy.
The scheduling rules consist of the following elements:
- Fixed loading and unloading durations for outbound and inbound activities:
Rule-based scheduling uses fixed loading/unloading times which are no longer based on the freight unit. Instead, they are based on the stop. Moreover, several freight units are treated as a one block that needs to be loaded or unloaded in its entirety, rather than individual items which need to be (un)loaded sequentially.
- Variable loading durations:
For a specific unit of measure you can define a loading duration. Just as an example, for each carton, 1 minute of loading time can be defined. In case the freight unit contains 6 cartons, the loading will take 6 minutes. This time is added on top of the fixed loading time, if defined. If necessary, the selection could even be limited further to a specific location, means of transport or vehicle type.
- Durations for preparation and finalization activities:
Durations can be set for other activities, e.g., preparation time at the start location, or time needed for completion tasks at the final location. In addition, the calendar resources with operating times can be set for these locations.
- Operating times or handling resources:
The operating times of specific handling resources or calendar resources can be set as well. Here, you can choose whether you want to use the location master data, or if you want to overwrite these values with specific operating times or specific handling resources. There is also the option to ignore constraints on operating times or handling resources altogether.
In addition to these rules, there are a few settings in the general data of the scheduling settings that could fine-tune the scheduling even more. These settings include:
- Consideration of the requirement document dates:
First, you can define how the dates on the freight unit are taken into consideration when performing scheduling. The standard option is to use the acceptable dates as hard constraints, whereas the requested dates are used as soft constraints. Secondly, you can choose to use the available dates as soft constraints only. That is, acceptable dates will be set as soft constraints when there are no requested dates available in the freight unit. You can also choose to ignore the freight unit dates altogether and use the freight order dates.
- Coupling/uncoupling durations:
This functionality works as with the VSS Scheduling. Whenever a TU is coupled, a coupling/uncoupling activity that can be scheduled is created.
- Attributes regarding the requirement document or location:
Based on specific characteristics of a location or a freight unit, you can influence the loading/unloading durations even further. For example, the rules to set the duration of loading and unloading may only be applicable if the freight unit contains dangerous goods.
What is the difference in configuration with VSS scheduling?
There are two important differences between the embedded scheduling functionality and the VSS scheduler.
One is that the setting ‘cost based requested dates/times’ is available to the embedded scheduler only but cannot be used by the VSS scheduler. The VSS scheduler will try and bring together all loading/unloading activities into the shortest period of time possible in order to avoid violation of the acceptable dates. In doing so, it will try to schedule within the requested time slots, but it may violate these as it doesn´t consider any earliness or lateness costs. The user can use scheduling directions (forward or backward scheduling) for the VSS scheduler to somehow steer this. For example, if an on-time delivery is very important, requested dates should be set for the end dates and backward scheduling should be used. Vice versa, forward scheduling and requested start dates should be used if pick-up dates must be respected.
The advantage of the embedded scheduler is that costs for earliness and lateness can be considered. This means that activities before the requested start or end date are more expensive, and the scheduler therefore will try to find a solution within the requested dates. The costs for earliness and lateness can be set in the ‘constraints and costs settings’ in the planning profile.
The second difference is that scheduling constraints that are defined in customizing cannot be used in combination with the embedded scheduler. For example, this means that with the embedded scheduler there is no opportunity to model driver breaks or driving times based on vehicle resources. If you have such a requirement and are planning to use the basic version of Transportation Management with the embedded scheduler, this is a disadvantage.
We are here for You!
In our next article we are going to have a closer look on how to use embedded scheduling in basic SAP TM and what the most important benefits of the feature are. In the meantime, please feel free to get in touch with us if you have any questions. Just send us an e-mail: firstname.lastname@example.org.
Anne van der Zwaag
Senior Consultant SAP Logistics
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