The Siemens "OPC Scout" is an OPC Client.
It will connect to any OPC Server.
You will need an OPC server that supports PPI to S7-200, and another OPC server that supports DF1 for SLC500.
For example, if you have RSLinx ("Single node", "OEM", "pro", "gateway", but NOT "lite"), then you can setup topics in RSLinx to point to the SLC500 via DF1. The Siemens OPC scout can then browse these topics.
RSLinx "OPC test client" does the same thing, as the Siemens "OPC Scout".