Utilize tools like SIMATIC Image & Partition Creator to make complete sector-by-sector backups of all OS and ES hard drives before initiating setup.
Contact your Siemens partner or account manager to purchase the appropriate upgrade licenses. Once purchased, install the V9.1 base software, then apply any service packs. The Maintenance Station Upgrade Package specifically supports upgrading from V9.0 to V9.1.
To obtain the latest installation files for SIMATIC PCS 7 V9.1, users must typically navigate through the Siemens Industry Online Support (SIOS) portal.
Always generate complete disk images of your engineering stations and back up your entire multi-project (including shared declarations and libraries) before running a new installer.