Cables
1. Direct connection
Use a direct connection if you don't need to monitor a existing serial connection. This way you can send the data from SerialMon.
Straight cable
Use a normal straight cable between your PC and a DCE (Data Communication Equipment). DCE is usually a modem.
Cable between PC and DCE device.
Crossed cable
Use a crossed cable between your PC and a DTE (Data Terminal Equipment).
Cable between PC and DTE device.