RS232-to-USB adapter with dial-up modem
 

Hi,

I have a RS-232 external dial-up modem that I use from time to time. It works fine when connected through a RS-232 port. I'd like to use the modem with another PC that doesn't have a RS-232 port, so I bought a RS-232 to USB adapter cable. It's a simple inexpensive cable that doesn't seem to have any chips/processors in it.

Now, when I connect the modem through a USB port I can't get the modem to work. It doesn't even attempt to dial the number:


# uname -a
Linux testbox 2.6.26-2-686 #1 SMP Mon Jun 21 05:58:44 UTC 2010 i686 GNU/Linux

# cat /var/log/syslog
....
Sep 17 02:44:12 testbox kernel: [363413.804010] usb 1-9: new full speed USB device using ohci_hcd and address 2
Sep 17 02:44:12 testbox kernel: [363414.008001] usb 1-9: configuration #1 chosen from 1 choice
Sep 17 02:44:12 testbox kernel: [363414.017176] usb 1-9: New USB device found, idVendor=1a86, idProduct=7523
Sep 17 02:44:12 testbox kernel: [363414.017181] usb 1-9: New USB device strings: Mfr=0, Product=2, SerialNumber=0
Sep 17 02:44:12 testbox kernel: [363414.017185] usb 1-9: Product: USB2.0-Serial
Sep 17 02:44:12 testbox kernel: [363414.133413] usbcore: registered new interface driver usbserial
Sep 17 02:44:12 testbox kernel: [363414.133431] usbserial: USB Serial support registered for generic
Sep 17 02:44:12 testbox kernel: [363414.133454] usbcore: registered new interface driver usbserial_generic
Sep 17 02:44:12 testbox kernel: [363414.133457] usbserial: USB Serial Driver core
Sep 17 02:44:12 testbox kernel: [363414.152941] usbserial: USB Serial support registered for ch341-uart
Sep 17 02:44:12 testbox kernel: [363414.152941] ch341 1-9:1.0: ch341-uart converter detected
Sep 17 02:44:12 testbox kernel: [363414.188064] usb 1-9: ch341-uart converter now attached to ttyUSB0
Sep 17 02:44:12 testbox kernel: [363414.188086] usbcore: registered new interface driver ch341
Sep 17 02:44:54 testbox pppd[32601]: pppd 2.4.4 started by luser, uid 2000
Sep 17 02:44:55 testbox chat[32602]: abort on (BUSY)
Sep 17 02:44:55 testbox chat[32602]: abort on (NO CARRIER)
Sep 17 02:44:55 testbox chat[32602]: abort on (VOICE)
Sep 17 02:44:55 testbox chat[32602]: abort on (NO DIALTONE)
Sep 17 02:44:55 testbox chat[32602]: send (ATZW2^M)
Sep 17 02:44:55 testbox chat[32602]: expect (OK)
Sep 17 02:45:00 testbox chat[32602]: SIGTERM
Sep 17 02:45:00 testbox pppd[32601]: Connect script failed
Sep 17 02:45:02 testbox pppd[32601]: tcsetattr: Interrupted system call (line 1010)
Sep 17 02:45:03 testbox pppd[32601]: Exit.
Sep 17 02:45:10 testbox pppd[32625]: pppd 2.4.4 started by luser, uid 2000
Sep 17 02:45:11 testbox chat[32626]: abort on (BUSY)
Sep 17 02:45:11 testbox chat[32626]: abort on (NO CARRIER)
Sep 17 02:45:11 testbox chat[32626]: abort on (VOICE)
Sep 17 02:45:11 testbox chat[32626]: abort on (NO DIALTONE)
Sep 17 02:45:11 testbox chat[32626]: send (ATZW2^M)
Sep 17 02:45:11 testbox chat[32626]: expect (OK)
Sep 17 02:45:56 testbox chat[32626]: alarm
Sep 17 02:45:56 testbox chat[32626]: Failed
Sep 17 02:45:56 testbox pppd[32625]: Connect script failed
Sep 17 02:46:36 testbox pppd[32625]: tcsetattr: Interrupted system call (line 1010)
Sep 17 02:46:37 testbox pppd[32625]: Exit.
Sep 17 02:46:42 testbox pppd[32647]: pppd 2.4.4 started by luser, uid 2000
Sep 17 02:46:43 testbox chat[32648]: abort on (BUSY)
Sep 17 02:46:43 testbox chat[32648]: abort on (NO CARRIER)
Sep 17 02:46:43 testbox chat[32648]: abort on (VOICE)
Sep 17 02:46:43 testbox chat[32648]: abort on (NO DIALTONE)
Sep 17 02:46:43 testbox chat[32648]: send (ATZW2^M)
Sep 17 02:46:43 testbox chat[32648]: expect (OK)
Sep 17 02:47:11 testbox chat[32648]: SIGTERM
Sep 17 02:47:11 testbox pppd[32647]: Connect script failed
Sep 17 02:47:12 testbox pppd[32647]: tcsetattr: Interrupted system call (line 1010)
Sep 17 02:47:13 testbox pppd[32647]: Exit.


Any ideas? Thanks





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RS232-to-USB adapter with dial-up modem
 

On Fri, 17 Sep 2010 00:42:26 -0700, S D wrote:

> I have a RS-232 external dial-up modem that I use from time to time. It
> works fine when connected through a RS-232 port. I'd like to use the
> modem with another PC that doesn't have a RS-232 port, so I bought a
> RS-232 to USB adapter cable. It's a simple inexpensive cable that
> doesn't seem to have any chips/processors in it.
>
> Now, when I connect the modem through a USB port I can't get the modem
> to work. It doesn't even attempt to dial the number:

(...)

Device is detected at "/dev/ttyUSB0".

Have you tried to communicate with the modem using low-level tools, such
"minicom"?

Greetings,

--
Camaleón


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RS232-to-USB adapter with dial-up modem
 

--- On Fri, 9/17/10, Camaleón <noelamac@gmail.com> wrote:
>
> Device is detected at "/dev/ttyUSB0".
>
> Have you tried to communicate with the modem using
> low-level tools, such
> "minicom"?

No. Anything in particular I should try? Thanks









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RS232-to-USB adapter with dial-up modem
 

On Fri, 17 Sep 2010 01:43:45 -0700, S D wrote:

> --- On Fri, 9/17/10, Camaleón wrote:
>>
>> Device is detected at "/dev/ttyUSB0".
>>
>> Have you tried to communicate with the modem using low-level tools,
>> such
>> "minicom"?
>
> No. Anything in particular I should try? Thanks

Nonthing special. Well, just that you can establish a dialog with your
modem by sending AT commands and even place calls. And minicom is perfect
for that :-)

If minicom is not able to dialog with your USB-converted modem, then the
problem can lie in hardware. If minicom just plays fine and communicates
well with your device, it could be a configuration/setup issue.

Greetings,

--
Camaleón


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