BernhardQ:
Prior commenting further, first it is needed to clarify a couple of things.
First, you try to share data over ethernet. You need to use a communication protocol (ModbusTCP or so) or as open standard (OPC or NetDDE) as ndzied1 explained. Your other computer should be able to "talk" this protocol.
Second, you try to somehow either save or log this data, to a file. Again there are several ways of doing this, either using VB, Excel,(with some programming) or using a logging software (I seen this in AutomationDirect ).
My guess is your controller is capable to share data. Look for libraries for that. Once you know what protocol you may use, continue on the second item, on "how to" save this data onto a file.
Best regards