How to provide custom number range for Serial Numbers

In standard way, when you generate serial number (for example in purchase order), system gives you very simple SNs, like 1, 2, 3 etc.

To have your own number range, proceed the next steps.

In t-code OIET (or SPRO: Plant Maintenance and Customer Service -- Master Data in Plant Maintenance and Customer Service -- Technical Objects -- Equipment -- Equipment Categories -- Maintain Equiment Category) create new equipment category (X for ex., copy from S)

In t-code OIEN (or SPRO: Plant Maintenance and Customer Service -- Master Data in Plant Maintenance and Customer Service -- Technical Objects -- Equipment -- Equipment Categories -- Define Number Ranges) define group and NR for group for object EQUIP_NR:

Assign group with NR to equipment category

In t-code OIS2 - create new serial number profile with equipment category X (SPRO: Plant Maintenance and Customer Service -- Master Data in Plant Maintenance and Customer Service -- Technical Objects -- Serial Number Management -- Define Serial Number Profiles) :

Inside profile, define Serializing procedures, where you will be generate SN, with Equipment Requirement = 02 always with equipment:

Create new material master with SN profile X001, Serialization Level = 1 Keep equipment number and serial number synchronous:

So, now in Purchase Order you can generate Serial Number from defined number range:

After PO save Serial Numbers keep in table EQUI.

If you do not see the button Create Serial Number Automatically, just check if Indicator: Serial Number Existence Requirement is OFF (OIS2 t-code):

If you create Purchase Order through  BAPI_PO_CREATE1 just populate SERIALNO field (SERIALNUMBER structure) by SN from external number range:

PO will be created with this Serial Number:

In case you populate UII in BAPI, system requires populate the batch and raises an error:

Serial number: maintain batch for batch management requirement

Message no. MEEXTFU021

Clean up UII and save PO.

Some additional info about the matter is here

http://saphelp.ucc.ovgu.de/NW750/EN/78/0eb753128eb44ce10000000a174cb4/frameset.htm