Siemens CP5512

Hello,

I'm trying to establish a connection between a laptom with CP5512 and a S7-200. First time I could manage to connect to the PLC, but next time I receive an error message: "Port could not be opened or is being used by another application".
Is the CP5512 out of order or I'm doing something wrong?

Regards

Restarting MicroWin might help. Also running Step7 & MicroWin simultaniously is known to cause trouble.