cygnulls

Add another big Thank You and success story. Rpi 2B, RJ45 to DB9 cable, DB9 RS232 to USB adapter. Almost 'off-the-shelf'. I still had the factory supplied ISY994 serial cable, but tx/rx have to be swapped. I didn't have a DB9 Null Modem adapter so I made a custom cable as you suggested using a patch cord and DB9 connector with screw terminals so no soldering at all. Both the 2448A7 and 2413U work perfectly. And thanks to all of the other contributors on this thread and others for their advice. I'm afraid to see what happens after power cycling, but hopefully this is temporary.