: For connections to S7-1500 (V2.9+) or S7-1200 (V4.5+) controllers, specific updates (Update 4 or higher) are required to handle "Secure Communication" protocols.
WinCC 7.5 SP2 is . Both Client and Server OS are listed separately. wincc 7.5 sp2 compatibility list
Projects from V7.2 or older must first be migrated to V7.4 before upgrading to V7.5. : For connections to S7-1500 (V2