Since firmware version 4.4 the SIMATIC S7-1200 supports OPC UA server natively. Just enable the server in your TIA project - TIA portal V 16 is required. See the slides below to update your S7-1200 to firmware 4.4. (Further information and German description on my company website Siincos Remote Connect - Remote Access and Management for Industry 4.0)

 

OPC UA S7 1200

 

pdf

OPC-UA-S7-1200

Size: 1.74 MB
Date modified: 2020-10-06