Hi, I found very annoying the fact that the SerialPort class in the .NET Framework doesn't allow to set the rts control to TOGGLE. There is a property called RTSEnable that lets me control directly the status of the RTS signal, but in a Compact Framework app there is not much precision to make it work well. Another solution can be to write a class that calls unmanaged APIs and set the rts control via the DCB structure, but I don't like it since I am using some external libraries that need to reference to a SerialPort instance. Have you any other idea ? Thanks !