Hello,

First you should prepare hardware configuration for S7-300 and CP343. After look at following FAQ: How do you configure an S7 connection for a user application via Industrial Ethernet with the SIMATIC NET PC software?. Then if everything is OK, look how to testing and using OPC Scout. http://support.automation.siemens.com/WW/view/en/13542666

Hope this will helps.

Best regards

Hristo Mihalev