I have only used hyperterminal to read serial data - so how is it interfaced through ethernet? Do they have some software that does serial-over-ethernet? If so, that really isn't going to work with an ML1100. MSG instructions would be used if the protocols are correct, but reviewing the specs it looks like they have a serial-to-ethernet application for a PC, and then a set of 'open sockets' for a custom protocol. To the best of knowledge, you can't do roll-your-own protocols with an ML1100. I think AB has an external ethernet device that supports a custom protocol, but I don't know if it is supported by an ML1100. I guess I would probably buy a Redlion part (Master Controller or G3 HMI) and write my own TCP driver to get the data out, then pass it to the ML1100 using the standard PCCC over EIP suite of protocols. That keeps everything ethernet.