Thanks Felipe and Greg for the replies. There is no one forcing us to use this kernel. Would http://releases.ubuntu.com/16.04.1/ubuntu-16.04.1-desktop-i386.iso.torrent?_ga=1.67231377.145502248.1467027188 be good enough to install? On Mon, Aug 29, 2016 at 6:19 PM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > On Mon, Aug 29, 2016 at 05:56:03PM +0530, Ajay Garg wrote: >> Hi All. >> >> We have a PC-in-a-box unit, with 2 COM-ports, 2 USB 2.0 ports and 1 >> USB 3.0 port. >> We are testing the COM-ports (COM1 and COM2) and the USB-ports. >> >> We proceeded as follows :: >> >> a) >> In the setup >> >> User-App <=> COM1 <=> RS232-data <=> RS232-to-RS485 converter <=> >> RS485-data <=> Modbus-Device >> >> when we send a modbus-command from user-app ==> modbus-device, we >> receive the modbus-response fine. (Of course, RS232 is enabled for >> COM1 in BIOS). >> >> >> b) >> If we modify the setup just a bit as >> >> User-App <=> USB-Port <=> USB-Serial-to-RS232 converter <=> Rs232-data >> <=> RS232-RS485 converter <=> RS485-data <=> Modbus-Device >> >> and then send a modbus-command from user-app ==> modbus-device, we DO >> NOT receive even a single byte as response. >> >> Very surprisingly, if we use the above setup in a USB-port of my >> personal laptop, we get the response fine (thereby signifying that >> that all elements from USB-Serial-to-RS232 converter <=> Rs232-data >> <=> RS232-RS485 converter <=> RS485-data <=> Modbus-Device are fine). >> >> >> Some more facts :: >> >> 1) >> uname -a gives identical output for my-laptop and the pc-in-a-box unit :: >> >> uname -a >> Linux blah-blah-login 3.16.0-30-generic #40~14.04.1-Ubuntu SMP Thu Jan >> 15 17:45:15 UTC 2015 i686 i686 i686 GNU/Linux > > First off, I suggest you get support from the distro you are using, as > they are the only ones that can give you that. This is a very old > kernel release and nothing that the community can help you out with, > sorry. > >> *So, now my question is that given the OS is identical and all >> "OS-drivers" same, what could be the difference in behaviour on >> pc-in-a-box and my-laptop? >> Are some usb-drivers present at hardware/motherboard level too, thus >> making the "difference in hardware" the root-cause (rather than >> "difference in software")?* > > If you are comparing the default use of a usb to serial converter to a > serial port on a motherboard, yes, they do sometimes work differently. > I would suggest checking your hardware flow control settings, lots of > usb-serial devices default to them enabled, while a "uart on a > motherboard" defaults to them disabled. Make sure you really are > setting everything up identically. > > If so, try a newer kernel release. Again, 3.16 is really old and > obsolete, we can help you out here if you use a 4.7 or newer kernel. > > thanks, > > greg k-h -- Regards, Ajay -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
