Hi Sk,
If u cancel your production order confirmation serial number will never get deleted, once u save ur order it will get updated in SER05 and even after this for the same material if you want assign the serial numbers you can, but the system will take the next serial number where it ended earlier.
By archiving complete stock u can reassign the same serial number or once the serial numbers are generated , system saves history-relevant document data together with the serial numbers. You can archive this serial number history using the archiving object PM_OBJLIST .
The archiving object PM_OBJLIST uses the archiving class PM_OBJLIST which archives and deletes data from all relevant tables like ..SER00,SER01,SER02,SER03,SER04,SER05........
System is automatically creating the equipment master while serial number is created.
Yes once serial number is created system will automatically updated EQUI table with serial number data also.
Hope this works for you
Thanks ,
vishal