CDC VCOM Driver location?

Hi! I know this has been discussed, but I’ve not seen an answer that provides clear direction, so…

Where does one get the CDC VCOM drivers needed for using a FEZ Spider and USB DP Client as a CDC VCOM port? This is what my computer’s looking for:


However, I have no .inf file that knows what driver to use. I’ve seen that the drivers are supposedly on my system, but would love to find the associated .inf.


The link in documentation of USB client CDC feature will send you to

Hi Gus, I’m sorry - I just can’t find that. The link you provided works clearly. (Thank you) But, I can’t find a document under the USB Client CDC page that points to it. Maybe I looked in the wrong place:>buy online->modules->usb dp client module->documents

Is that what you’re refering to?

Look at the documentation USB Client → CDC

Here is a link

Ah - I see. I thought it would be linked near the example tutorial code. But, it’s in the NETMF docs. Thanks for the clarification.

I made a .inf file and copied it into the following directory:

C:\Program Files (x86)\GHI Electronics\GHI Premium NETMF v4.2 SDK\USB Drivers\GHI_NETMF_WinUsb

Is that needed? Or can I just put the .inf wherever convenient?

Also, I now see a com port for the CDC VCOM device. But, using putty (what a great program) I can’t open that serial port. I checked the speed, parity, bits, etc and that all matches. (I am successful in using putty for a BT SPP connection.

Any pointers?

Strange. Can you try teraterm?

Sure. Downloaded, unzipped it and installed it. Changed the VCOM port to 2, since Tterm only works with ports 1-4 and 3&4 are already in use.

Same result: can’t open serial port.

A puzzler…

Oh - and now that I’ve installed the VCOM driver, the code thinks it’s connected and writes to the (non-existent) serial device (well, non-visible) :slight_smile:

And, some more info: Win7, 64 bit OS.

Hello, I tried a simple example and see that it is working well. Test on Win7 - 64bit too

[quote]Tterm only works with ports 1-4 and 3&4 are already in use.[/quote] => You mean TeraTerm? on my side port 45# is good.

This is the teraterm we use

I’m traveling, but will download the (greatly) updated TTerm and try it as soon as I can. Like Dat, I see the device in the device manager as a CDC device, on whatever port. But, when I try to use a terminal program, it doesn’t hook up. Thanks for the new pointer, and I’ll let you know what happens!

Interesting. If I use the code sample, which merely streams a connected message, I can make that work. But, if I try the following:

            int i = 0;
            byte[] bytes = System.Text.Encoding.UTF8.GetBytes("Connected to FEZ Spider!" + i++.ToString() + "\r\n");
            // Check if connected to PC
            while (true)
                while (USBClientController.GetState() != USBClientController.State.Running)
                    debugLCD.Print("Waiting to connect to PC...");
                debugLCD.Print("Connected via CDC");
                cdc.Write(bytes, 0, bytes.Length);

I see on my DebugLCD output that I am connected. However, I never get output in the serial terminal.

And, is there a way to know that someone has send data to the CDC port? That is, some callback like bt.DataReceived += new Bluetooth.DataReceivedHandler(bt_DataRcvd); for bluetooth?

For receiving, you need a thread that loops every 10ms and read the data.

thanks, Gus. Any thoughts on why output doesn’t show up?

No but Dat maybe able to help

I checked and it seems we have a problem with CDC VCOM driver. we are looking into it further.
Thanks for your feedback.

Looking forward to a resolution. :slight_smile:

Is there a prize for finding problems?

What about some beer? :slight_smile:

@ Gus - Sign me up… One beer for the VCOMM driver problem and one for the persistent storage problem. :slight_smile:

@ Dat - Any updates on this topic?

@ jzeevi -

One beer for the VCOMM driver problem and one for the persistent storage problem. :slight_smile:

what is “persistent storage problem”?