Supply Chain Units?!?!?! If you wonder what this is, it is actually no problem for somebody working with SAP TM. You will not find them in the menu, nothing in the TM documentation. And obviously you had no issues with them yet. So why care?
Supply Chain Units (SCU) are master data objects meant to unify Locations, special positions like doors, and also Transportation Zones. The standard transaction code is /n/SCMB/SCUMAIN. The object itself is not used in SAP TM, but for SAP EWM. Nevertheless, as both applications sit on top of the SCM basis, the SCUs exist also in SAP TM systems. And here comes the point: Sometimes when creating Locations or Transportation Zones, a strange message saying that a Supply Chain Unit with the very same ID already exists pops up. Also when deleting Locations or Transportation Zones, such situations occur. So it is a question of master data consistency which might require a bit of understanding regarding SCUs.
A few years back I spend some time decoupling all master data objects for the transportation network, so SAP TM really does not require any information stored on SCU level.
Basically, whenever a Location or Zone is created, also a SCU with the same ID and technical GUID is created. So after saving your Location you can go to /n/SCMB/SCUMAIN and check it out. On DB level it is table /SCMB/TOENTITY. This table is quite interesting as it is the only SCMB master data table having both technical GUID formats (X16 and C22) in it. So it can be used to skip the GUID conversion by directly joining tables using SQL. But I guess it gets to techi now…
So whenever you run into network inconsisitency issues, this could be a spot to check. Using the SCU transaction you can adjust the object or even makr it for deletion. Be carefull with what you do there though.
As the tight integration between SAP TM and SAP EWM will become more and more important in the future, the SCU might also become directly relevant for SAP TM. Just imagine a scenario of a truck planned by SAP TM arriving at a certain gate (SCU) in EWM. Great stuff for a SAP Visual Business show case.