External Dail-Up USB-to-Serial Modem Hangs and Requires Reboot To Fix

S

ShadowTek

I have an external serial modem that is run through a serial-to-USB
converter.
http://www.newegg.com/Product/Product.aspx?Item=N82E16825134002
http://www.newegg.com/Product/Product.aspx?Item=N82E16812107956
&Tpk=trendnet%2busb%2bserial

It will occationally hang, and the the only way to get back control of the
modem is to reboot the computer. When I query to modem from the control
panel, it says: "The port that the modem is using is currently open by
another application. Exit any application that may currently be using the
port."

I don't know what could be causing the problem. I have tried disabling all
other needless applications that run in the background, but that is still
no change.

Anybody got any ideas of other things that I can try?
 
A

Andrew E.

Serial ports & paralel ports seem obsolete these days,why not purchase
a USB modem,the interface is much faster.
 
S

ShadowTek

Serial ports & paralel ports seem obsolete these days,why not purchase
a USB modem,the interface is much faster.

It's just a dailup modem, so I don't need a faster interface. Besides, I
bought this so that it would work with both Windows and Linux, as I have
already gone through hell trying to get the old soft modem to work with
Linux.

I also wanted to have a serial modem around in case I needed to use it with
any older computers.

Besides, there's no sense in spending any more money if I don't know what
the problem is. I might buy and install a new hardware modem just to end up
having the same persistant issue to deal with.
 
V

V Green

FWIW, I use a USB-SER cable to use my
Kyocera cellphone as an AT-compatible modem,
not quite the same, but a similar situation.

If the connection barfs, I also have to restart the system
to clear the "port is already open" stuff. Even unplugging
and reconnecting the USB-SER cable won't do it. So, it's a
problem likely not specific to your setup, but more of
a flaw within the driver for the USB adapter cable.

You might try this (just occurred to me and I haven't):

Next time it happens, disable then enable the USB-SER
hdwe. from Device Manager.
 
S

ShadowTek

FWIW, I use a USB-SER cable to use my
Kyocera cellphone as an AT-compatible modem,
not quite the same, but a similar situation.

If the connection barfs, I also have to restart the system
to clear the "port is already open" stuff. Even unplugging
and reconnecting the USB-SER cable won't do it. So, it's a
problem likely not specific to your setup, but more of
a flaw within the driver for the USB adapter cable.

You might try this (just occurred to me and I haven't):

Next time it happens, disable then enable the USB-SER
hdwe. from Device Manager.

The problem is that I need some kind of automated solution to the problem,
so that I can keep my connection active as much as possible. I thought
that, if nothing else, I could make some kind of script that would
periodically check for successful pings to various servers, and if all
pings failed, then the modem has hung, and the system can be automatically
rebooted. The problem with this idea is that the system sometimes get hung
so bad that I can't do a soft reboot. And if I can't do a soft reboot, then
I can't automate the process.
 
V

V Green

ShadowTek said:
The problem is that I need some kind of automated solution to the problem,
so that I can keep my connection active as much as possible. I thought
that, if nothing else, I could make some kind of script that would
periodically check for successful pings to various servers, and if all
pings failed, then the modem has hung, and the system can be automatically
rebooted. The problem with this idea is that the system sometimes get hung
so bad that I can't do a soft reboot. And if I can't do a soft reboot, then
I can't automate the process.

I believe that I have seen code to disable/enable devices
that show up in Device Manager. If disabling/enabling
the port/cable revives the device then you could go this
route rather than rebooting the entire system. Try Google.

Also, it isn't necessary to ping things to find out whether
or not the modem has hung. Simply issuing an AT command
and looking for the OK response (after enabling verbose mode,
etc.) will keep things local. No OK, no comm.

For testing purposes, you can probably initiate a "hung"
state by disconnecting the RJ-45 cable from the modem while
it's in use. Or by pulling the USB cable from the computer
while off-hook.

If that works, you have all the necessary tools to write your
own custom solution, which it sounds like you will need to
do, given the description of your situation.
 
S

ShadowTek

I believe that I have seen code to disable/enable devices
that show up in Device Manager. If disabling/enabling
the port/cable revives the device then you could go this
route rather than rebooting the entire system. Try Google.

Also, it isn't necessary to ping things to find out whether
or not the modem has hung. Simply issuing an AT command
and looking for the OK response (after enabling verbose mode,
etc.) will keep things local. No OK, no comm.

For testing purposes, you can probably initiate a "hung"
state by disconnecting the RJ-45 cable from the modem while
it's in use. Or by pulling the USB cable from the computer
while off-hook.

If that works, you have all the necessary tools to write your
own custom solution, which it sounds like you will need to
do, given the description of your situation.

I found a Microsoft application, called DevCon, that claims to give command
line control over devices.
http://support.microsoft.com/kb/311272
I'll play with that if simply disabling the device solves the problem.
Thanks.
 
S

ShadowTek

I believe that I have seen code to disable/enable devices
that show up in Device Manager. If disabling/enabling
the port/cable revives the device then you could go this
route rather than rebooting the entire system. Try Google.

Also, it isn't necessary to ping things to find out whether
or not the modem has hung. Simply issuing an AT command
and looking for the OK response (after enabling verbose mode,
etc.) will keep things local. No OK, no comm.

For testing purposes, you can probably initiate a "hung"
state by disconnecting the RJ-45 cable from the modem while
it's in use. Or by pulling the USB cable from the computer
while off-hook.

If that works, you have all the necessary tools to write your
own custom solution, which it sounds like you will need to
do, given the description of your situation.

It happened again. I tried disabling the modem, but there was no change. I
also tried disabling the serial to USB adapter, but that also did nothing.
And, once again, I could not soft reboot, so I can't figure out any other
way to automatically deal with the problem.
 
V

V Green

ShadowTek said:
It happened again. I tried disabling the modem, but there was no change. I
also tried disabling the serial to USB adapter, but that also did nothing.
And, once again, I could not soft reboot, so I can't figure out any other
way to automatically deal with the problem.

Time for different / newer hardware, sounds like.
 

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