Have updated to V2.77, no change. disabled RTS/CTS, no change. With PA connected to Com 1 rotator worked on Com 2 mode 5, 4800, 8/1 hex 3b. Have also tried mode 3, 4800, 8/1 hex 00. Have switched rotator control unit between com 1 and com 2, no difference. Am using Vlinx ethernet/rs232 server for CAT control which works fine. Tried changing com2 to same parameters as Vlinx and switced CAT to COM2 - doesnt work. Looks like COM2 just will not work without amp connected to Com 1, which does not make sense! Could be a while before I get the amp back so any help to get rotator working would be greatly appreciated.