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Re: (ASCEND) usr x2 and 4048

Rob Williams wrote:
> 
>         Has anyone seen disconnect problems on the max 4048
> specific to USR x2 modems?? Seems when my X2 users roll over
> to my ascends, they complain about disconnnects. I dont have
> any complaints from customers who use non x2 modems. I know
> that the x2 modem will receive a v.34 rate on the ascend, which
> is fine, but disconnects are not. Seems they should be able to
> handle a regular v.34 connection. Any ideas? Help is greatly
> appriciated. This particular Max is running 4.6CCi24 and the
> old v.34 modems.
> 
> robw@dnai.com
> 
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This is usually the problem and here is the fix:



        Disconnects

             Firmware, init strings, and drivers 

             Too many devices on the phone line 

             Lowering connect speed with K56flex 

             External PC modems 

             Macintosh issues 

             USR Sportsters get slower and slower, and may disconnect
suddenly

          

        Disconnects

          



        Firmware, init strings, and drivers

        Many disconnect problems can be solved by loading a more recent
version of the firmware. Check the firmware
        page. 

        Likewise, having the correct modem init string or driver
installed is important. Check the inits and drivers page. 



        Too many devices on the phone line 

        It's possible to have too many devices on your phone lines or
extension. Try unplugging extra phones, fax machines,
        and answering machines to see if the disconnects stop. 



        Lowering connect speed with K56flex

        Some K56flex owners have found that they can reduce disconnects
by setting a limit on the initial connect speed.
        The commands for controlling maximum connect speed are different
for Rockwell-based and Lucent-based
        K56flex modems. 

        On Rockwell-based K56flex modems 

        If you normally get disconnected when you connect at 48000, you
might try using: 

        +MS=56,0,9600,46000 

        If that didn't work, you would try: 

        +MS=56,0,9600,44000 

        +MS=56,0,9600,42000 

        and so on, reducing the maximum connect speed by 2000 each time.
Experiment with different numbers to see if
        lower numbers result in fewer disconnects. 

        On Lucent-based K56flex modems 

        The S38 command can be used to control the maximum connect
speed. The values between 2 and 14 set the
        maximum speed between 32K and 56K. So, if you normally get
disconnected when you connect at 48000, you
        would try: 

        S38=9 

        to set the maximum connect speed to 46000. If you still get
disconnected, you might try: 

        S38=8 (for 44000) 

        S38=7 (for 42000) 

        and so on. 



        External PC modems

        Older PCs may have weak UARTs that are not capable of high speed
communications. As a result, you may get
        frequent dropped connections and/or poor modem performance due
to resent packets. 

        To test this, try lowering your connect speed to 38400 or even
19200. If the dropped connections cease, a slow
        UART may be the problem. A replacement serial port card should
fix the problem. 

        For use with a 56K modem, you want at least 16550 UART. Internal
56K modems should include a 16550 or
        higher UART on the card. 



        Macintosh issues

        The Macintosh uses an 8-pin serial port, rather than the 9- or
25-pin port on most other computers. As a result,
        Mac modem cables handle DTR differently, and DTR is often used
as a disconnect signal. 

        The classic symptom of unwanted DTR disconnect on the Mac is
getting knocked offline when receiving a large
        stream of data. This may happen during a download, or when
issuing a dir command in a command-line FTP
        program. 

        To disable DTR hangup, add &D0 (zero) to the end of your init
string. 

USR Sportsters get slower and slower, and may disconnect suddenly

This is the x2 version of Spiral Death Syndrome. The fix in most cases
is to add S15=128 to the init string to disable V.42 hardware error
correction. It may also be necessary to add &K0 to the init string to
disable V.42bis hardware data compression, though this should be a last
resort, as performance will suffer when downloading non-compressed
files. 

Good Luck

Bill
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