Hi, Ajay Garg <ajaygargnsit@xxxxxxxxx> writes: > 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. which kernel is running on this PC-in-a-box unit? > 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 > > 2) > On the pc-in-a-box-unit, following are some diagnostics that I could think of :: > > lsmod | grep usb > usbnet 37829 1 qmi_wwan > mii 13654 1 usbnet > usb_wwan 19306 1 qcserial > usbhid 47035 0 > hid 95946 3 i2c_hid,hid_generic,usbhid > usbserial 38972 8 qcserial,pl2303,usb_wwan > > lsmod | grep pl2303 > pl2303 18516 0 > usbserial 38972 8 qcserial,pl2303,usb_wwan > > 3) > The USB-Serial-to-RS232 converter information :: > > lsusb > Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub > Bus 001 Device 007: ID 1199:68a2 Sierra Wireless, Inc. > Bus 001 Device 005: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB > Bus 001 Device 004: ID 413c:2107 Dell Computer Corp. > Bus 001 Device 003: ID 046d:c05a Logitech, Inc. M90/M100 Optical Mouse > *Bus 001 Device 002: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port* > Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub > > > 4) > The checksums of the following drivers are identical on the > pc-in-a-box unit and my-laptop :: > > cksum /lib/modules/3.16.0-30-generic/kernel/drivers/usb/serial/usbserial.ko > 425603799 59904 > /lib/modules/3.16.0-30-generic/kernel/drivers/usb/serial/usbserial.ko This kernel is over 2 years old. You need to ask for suport from whoever's forcing you to use this kernel. -- balbi
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