topic Re: modem - usb to serial configuration in Operating System - Linux

modem - usb to serial configuration

Jeff Hoevenaar — Fri, 02 Dec 2005 14:32:22 GMT

I have a serial modem connected to a usb port using a adapter cable. The systems is a HP DL360.

I am using the device /dev/ttyUSB0

When I issue the command "mgetty ttyUSB0" I get the following output in the log file.

How do I get the system to see the modem.

12/02 14:17:55 SB0 mgetty: experimental test release 1.1.30-Dec16
12/02 14:17:55 SB0 check for lockfiles
12/02 14:17:55 SB0 locking the line
12/02 14:17:56 SB0 WARNING: DSR is off - modem turned off or bad cable?
12/02 14:17:56 SB0 lowering DTR to reset Modem
12/02 14:17:56 SB0 send: \dATQ0V1H0[0d]
12/02 14:17:57 SB0 waiting for ``OK''
12/02 14:18:17 SB0 timeout in chat script, waiting for `OK'
12/02 14:18:17 SB0 init chat timed out, trying force-init-chat
12/02 14:18:17 SB0 send: \d[10][03]\d\d\d+++\d\d\d[0d]\dATQ0V1H0[0d]
12/02 14:18:21 SB0 waiting for ``OK''
12/02 14:18:41 SB0 timeout in chat script, waiting for `OK'
12/02 14:18:41 SB0 init chat failed, exiting...: Interrupted system call
12/02 14:18:41 ##### failed in mg_init_data, dev=ttyUSB0, pid=28154

Re: modem - usb to serial configuration

Jeff Hoevenaar — Fri, 02 Dec 2005 15:56:35 GMT

Where do i get the vaules for this command (VVVV and PPPP)?

I have a Multitech serial modem.

insmod usb-serial.o vendor=0xVVVV product-0xPPPP

Re: modem - usb to serial configuration

Thomas Bianco — Mon, 05 Dec 2005 10:27:19 GMT

looking at the script, it looks like there is a disconnect between the device node and the modem itself.

a few things you can try:

attach to the serial device with serial console (like XComm, GTKTerm, or similar) and see if you can send any data. try the same with a VT or another computer attached instead of the modem. success indicates a problem with your mgetty setup or modem, failure indicates a problem between the serial output and the device file

attach the modem to a real serial port and see if you can talk to it with a serial console. success validates the modem, failure sends you to the hardware shop for a new one.

the fact that the mgetty complains about DTR off suggests there is a problem with the USB device.

check the serial howto (http://tldp.org/HOWTO/Serial-HOWTO.html) and the USB howto (http://www.linux-usb.org/USB-guide/p13.html) for some troubleshooting steps.

Re: modem - usb to serial configuration

Alan_152 — Mon, 05 Dec 2005 12:16:11 GMT

A modem, despite it being connected through a USB port, should still show up as a serial device (COM or SER).