Understand SAP EWM

The purpose & functionalities of wave templates

Note: This post belongs to the blog-series ‘Understand SAP EWM the purpose & functionalities of wave template in SAP EWM’. The purpose of these series of blog-posts is to explain the concept of the core features of SAP EWM in a simple way. It is intended to target EWM beginners and focuses on the basic understanding rather than the smallest details which will be communicated as part of future posts for more advanced users.

Again we start with our warehouse request. Please refer to the post about wave & resource management to get a basic understanding of the terms warehouse request & warehouse request items.

And again we – and also EWM – are only interested in the warehouse request items. So let us consider our bucket of warehouse request items for the following explanations:

This bucket represents our total workload. Now we need to decide which parts of this total workload should be processed at what times respectively in which time windows: But how do we get here? Exactly at this point we make use of so called Wave Templates.

To understand the functionalities around wave templates & wave template determination in SAP EWM we will use an analogy. Imagine a group of commuters having to come to their workplace in the morning via public transportation. Each of the individual commuters has his or her own requirements:

Where do I have to be picked up?
What time am I able to be at the bus station and what time do I need to be at my destination?
What company am I working for? (it might provide a dedicated bus for the employees)
Which class do I want to travel?

On the other hand, imagine different bus lines being available for those commuters. These bus lines have different characteristics and offerings. They are

running on different schedules with different frequencies
driving with different speed
offering different service levels
applying different kind of treatments in case one of the passengers does not have a ticket

Now we need to decide which of the commuters is going to take which bus line and – one step further – which run from all the different runs that are offered by each line. In SAP EWM the bus line is our wave template and the run of the bus line is our wave template option. The specific bus which is executing the given run for this line will later is our wave. So as mentioned above, this is exactly what is happening here:

In the first step we check for each individual commuter where he or she has to be picked up, which class he/she wants to travel, what is his/her following connection etc.. Based on this we decide which bus line should be taken. So in EWM we decide for each warehouse request item which wave template should be applicable. Technically SAP EWM is making use of the condition technique for the determination of the wave template. Basically, all data from delivery header & item can be considered as part of the condition tables (not everything is available standard condition tables but can be added via standard procedures of enhancing condition tables). So instead of checking the starting point and the travel preferences of our commuter we do here check the source activity area, route, document type, delivery priority, warehouse process type etc. of each warehouse request item. In the second step we check the schedule of the given bus line and compare it with times our commuter has to be at his connection bus stop or workplace (plus we check the time when he/she is able to be at the departure bus stop). We do this to determine which run of the line is most appropriate for each individual commuter. In EWM – we check which wave template option is most suitable for our warehouse request item. Technically, EWM is comparing the planned GI date (in fact it is comparing the planned date/time for departure from yard but usually you map your planned GI date/time from ERP to this date type) with the times from the wave template option. Each wave template has one (or more) different options in the same way as a bus line has busses running at different times (above we called this the ‘runs’ of the bus line). So each wave running a specific option represents a bus operating one of the runs from the schedule:

So this template option – respectively our bus – decides now

at what time it starts (so basically the latest possible time when the commuter must be at the bus station) -> Some drivers are very friendly and do