Hello nicaveman,
If you are looking for an ethernet to serial converter, take a look at our
Ethernet Serial Interfaces.
If you are looking for more of a multifunction DAQ device (something that can do analog or digital input/output) with ethernet capability, take a look at
Compact FieldPoint. There are a variety of modules that offer you a wide range of input/output functionality. You can also use one of the controller interfaces if you need to embed a real-time application.
Hope this helps!