Posted on December 15, 2016 at 16:05' how can I configure the speed? '
Down the USB wires - I don't believe you do... I think of it this way.
On a USB 2.0 FS(Full Speed) capable implementation, the data on the USB wires is ---12Mbps ---. No matter WHAT the com port setting are. That's FS speed on the USB wires. Now more in depth - those COM PORT settings are generally to do with a VIRTUAL COM PORT that gets configured when you plug in a USB device that enumerates and installs as a VIRTUAL COM PORT ( Like a USB to RS232 converter). THAT type of device at the RS232 side has - surprise - A UART!
Those com port settings are pushed to THAT uart during a control endpoint communication during USB device setup.
Now lets say you have a device that is NOT a USB to RS232 converter. (Presumably something like YOU have). You may have a USB controlled LED blinker... And you just want to get data from the PC to your device. And you lean on your COM PORT knowledge and see this VCP capability. Well since your END DEVICE is not using a UART but can make use of the VCP style connection and data transfer, then - the com port setting don't matter... You still get the USB transferred data. Data transfer emulation is somewhat emulated with either full packet detection or timeouts. IF a USB TX buffer has a full load in it, it gets transmitted NOW if the receiver isn't nacking it. (Flow control emulations) OR if a TX buffer has say - 1 byte in it and a timeout occurs (1ms maybe) the USB transmitter fires the byte down the usb wires.
Needless to say - A LOT going on behind the scenes. That's a rough idea. And I could be wrong. And things vary.
USB - Be prepared to learn a LOT.
