How, exactly, does CentOS-6.3 with udev recognize an USB modem when it is plugged in. How is it indicated? What other configuration is required?
I can find the modem in /sys/class/tty and I can get the attributes using udevadm but I do not see anything in ps that refers to the modem device.
On Wed, October 17, 2012 12:49, James B. Byrne wrote:
How, exactly, does CentOS-6.3 with udev recognize an USB modem when it is plugged in. How is it indicated? What other configuration is required?
I now have the subject modem device attached to a kvm guest instance. I can connect to it from the guest using picocom. I can see the TR light go on. I cannot find a baud rate with which to issue AT commands.
If I use a baud rate of 38400, 57600 or 115200 and issue ATI then I get back a variable number of unprintable (white question mark on black background mostly) characters, with 115200 returning the longest string. If I use any rate below 38400 I see nothing.
# picocom -b 115200 /dev/ttyACM0 picocom v1.6
port is : /dev/ttyACM0 flowcontrol : none baudrate is : 115200 parity is : none databits are : 8 escape is : C-a local echo is : no noinit is : no noreset is : no nolock is : no send_cmd is : sz -vv receive_cmd is : rz -vv imap is : omap is : emap is : crcrlf,delbs,
Terminal ready ����������֮͠����Թ��������� ������������������������썊������ҍ�
The same modem responded correctly to ATI commands issued in a 9600 baud picocom connection when the modem was attached to the host system.
# picocom /dev/ttyACM0 picocom v1.6
port is : /dev/ttyACM0 flowcontrol : none baudrate is : 9600 parity is : none databits are : 8 escape is : C-a local echo is : no noinit is : no noreset is : no nolock is : no send_cmd is : sz -vv receive_cmd is : rz -vv imap is : omap is : emap is : crcrlf,delbs,
Terminal ready ATI Agere OCM V.92 MT9234ZBA-USB Data/Fax Modem Version 1.02l
Does anyone have any idea what is happening and how to correct this?
On Thu, October 18, 2012 11:46, James B. Byrne wrote:
On Wed, October 17, 2012 12:49, James B. Byrne wrote:
How, exactly, does CentOS-6.3 with udev recognize an USB modem when it is plugged in. How is it indicated? What other configuration is required?
I now have the subject modem device attached to a kvm guest instance. I can connect to it from the guest using picocom. I can see the TR light go on. I cannot find a baud rate with which to issue AT commands.
P.S.
# wvdialconf Editing `/etc/wvdial.conf'.
Scanning your serial ports for a modem.
ttyS0<*1>: ATQ0 V1 E1 -- failed with 2400 baud, next try: 9600 baud ttyS0<*1>: ATQ0 V1 E1 -- failed with 9600 baud, next try: 115200 baud ttyS0<*1>: ATQ0 V1 E1 -- and failed too at 115200, giving up. Modem Port Scan<*1>: S1 S2 S3 WvModem<*1>: Cannot get information for serial port. ttyACM0<*1>: ATQ0 V1 E1 -- OK ttyACM0<*1>: ATQ0 V1 E1 Z -- OK ttyACM0<*1>: ATQ0 V1 E1 S0=0 -- OK ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 -- OK ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 -- OK ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK ttyACM0<*1>: Modem Identifier: ATI -- Agere OCM V.92 MT9234ZBA-USB Data/Fax Modem Version 1.02l ttyACM0<*1>: Speed 4800: AT -- OK ttyACM0<*1>: Speed 9600: AT -- OK ttyACM0<*1>: Speed 19200: AT -- OK ttyACM0<*1>: Speed 38400: AT -- OK ttyACM0<*1>: Speed 57600: AT -- OK ttyACM0<*1>: Speed 115200: AT -- OK ttyACM0<*1>: Speed 230400: AT -- OK ttyACM0<*1>: Speed 460800: AT -- Speed 460800: AT -- Speed 460800: AT -- Max speed is 230400; that should be safe. ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- and failed too at 115200, giving up.
This issue is not resolvable in the current release of RHEL6 nor is it likely to be fixed before RHEL7, if then.
https://bugzilla.redhat.com/show_bug.cgi?id=868309
Ademar de Souza Reis Jr. 2012-10-22 09:01:58 EDT
Deferring to RHEL7 because this is a complex fix.
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James B. Byrne