What Intel Galileo are you using (either "Intel Galileo" or "Intel Galileo Gen2")? Take a look at , where some differences are explained specifically on FTDI cables.
Did you install the corresponding Intel Galileo driver?
Did you upgrade the Intel Galileo firmware?
I am using galileo gen 2. My FTDI cable is 3.3v TTL UART serial cable,connector end,1.5m,TTL-232R-3v3 and yes i have installed the corresponding drivers and updated the galileo firm ware as well. Well me and my friend both did it but on mine there is CDC serial port error as well and on his system their is no CDC serial port error but still putty terminal doesn't open up.
I see... let me see if I can help...
Please unplug everything, open the device manager and send a screen capture in this state.
Then, plug in the USB connected to the Intel Galileo Gen2 FTDI, and send a screen capture showing the device manager in this state.
Take into account that the Intel Galileo (and Intel Galileo Gen2) serial connection is not related to the driver needed to program the Intel Galileo (and Intel Galileo Gen2) via the Arduino IDE. Your serial connection should be seen as a COM port regardles of the CDC serial, AFAIK.
his is the screenshot that shows device manager before connecting anything
This screenshot contains device manager after connecting FTDI cable
NOTE - THIS IS THE SYSTEM WHICH IS NOT HAVING ANY CDC SERIAL ERROR.
Right, this is how it has to be so far. Now, it seems to be that your card connection through the USB is recognized in COM4 thus, you should use PuTTY or any other similar program to connect to your card. Remember the settings you should use:
a) The com port in which your card connection is recognized
b) 115200 bauds
c) Serial connection
In case you use PuTTY, settings should look like this: