Texas 545 integration

I am looking at upgrading a scada package hanging of a serial link to an old texas 545 PLC.
What I would like to do is develop the new scada screens on another machine over ethernet

Does anyone know of any products that you have heard about or used to aggregate the serial coms to another serial port and ethernet.
I have looked at using a redlion data station- but would welcome comments on any experiences out there

I think you are on the right track with Red Lion DSP, I've used one and they are simple to use and install

Why not add a true ethernet module?
CTI sells a 10mb and 100mb version.