On 5/22/2012 2:07 PM, Paul Rubin wrote:
John Nagle<[email protected]> writes:If a device is registered as /dev/ttyUSBnn, one would hope that the Linux USB insertion event handler, which assigns that name, determined that the device was a serial port emulator. Unfortunately, the USB standard device classes (http://www.usb.org/developers/defined_class) don't have "serial port emulator" as a standardized device. So there's more variation in this area than in keyboards, mice, or storage devices.Hmm, I've been using USB-to-serial adapters and so far they've worked just fine. I plug the USB end of adapter into a Ubuntu box, see /dev/ttyUSB* appear, plug the serial end into the external serial device, and just use pyserial like with an actual serial port. I didn't realize there were issues with this.
There are. See "http://wiki.debian.org/usbserial";. Because there's no standard USB class for such devices, the specific vendor ID/product ID pair has to be known to the OS. In Linux, there's a file of these, but not all USB to serial adapters are in it. In Windows, there tends to be a vendor-provided driver for each brand of USB to serial converter. This all would have been much simpler if the USB Consortium had defined a USB class for these devices, as they did for keyboards, mice, etc. However, this is not the original poster's problem. John Nagle -- http://mail.python.org/mailman/listinfo/python-list
