9600bps transparent connection?
Jose V. Gavila
I am trying to get a 9600bps transparent connection:
Local PC <-> Local modem <-> PHONE LINE <-> Remote modem <-> Remote
system
9600 9600 ?
Local PC runs an application which communicates with the local modem at
9600bps. Then line speed is also 9600bps. But on remote end, RING
indications are received at 9600 but, as soon as the connection is
stablished, its speed to remote device changes to 38400bps (I have
checked that with the oscilloscope)
I wonder how can I get also 9600bps on remote end as it is the only way
my remote system will work fine.
Local modem is a Zoltrix 56k v90 and remote modem is a US Robotics 56k
Thanks for any help!
Regards,
JOSE
Hooda Gest
"Jose V. Gavila" <eb5...@ctv.es> wrote in message
news:3F279613...@ctv.es...
> Hello!
>
> I am trying to get a 9600bps transparent connection:
>
> Local PC <-> Local modem <-> PHONE LINE <-> Remote modem <-> Remote
> system
>
> 9600 9600 ?
>
> Local PC runs an application which communicates with the local modem at
> 9600bps. Then line speed is also 9600bps. But on remote end, RING
> indications are received at 9600 but, as soon as the connection is
> stablished, its speed to remote device changes to 38400bps (I have
> checked that with the oscilloscope)
38400bps is a port speed, not a modem speed. Lock the port speed to 9600bps
if that's what you think you need. Set modem not to "autobaud"
>
> I wonder how can I get also 9600bps on remote end as it is the only way
> my remote system will work fine.
>
> Local modem is a Zoltrix 56k v90 and remote modem is a US Robotics 56k
Set port (DTE) speed to 9600bps if that is what the software requires. In
the USR, make sure &B1 is set (it should be default); that will limit the
USR to a max DCE (modem to modem) speed of 9600bps. The Zoltrix should also
follow that limit and that port speed should also be set to 9600bps.
Again, all of the above is based upon the assumption that, for who knows
whatreason, the software wants to communicate with the ports at 9600bps.
--
Hooda Gest
"In a New York minute, everything can change..."
Aaron Leonard
~ >
~ > Local PC <-> Local modem <-> PHONE LINE <-> Remote modem <-> Remote
~ > system
~ >
~ > 9600 9600 ?
~ >
~ > Local PC runs an application which communicates with the local modem at
~ > 9600bps. Then line speed is also 9600bps. But on remote end, RING
~ > indications are received at 9600 but, as soon as the connection is
~ > stablished, its speed to remote device changes to 38400bps (I have
~ > checked that with the oscilloscope)
~ 38400bps is a port speed, not a modem speed. Lock the port speed to 9600bps
~ if that's what you think you need. Set modem not to "autobaud"
~
~ >
~ > I wonder how can I get also 9600bps on remote end as it is the only way
~ > my remote system will work fine.
~ >
~ > Local modem is a Zoltrix 56k v90 and remote modem is a US Robotics 56k
~
~
~ Set port (DTE) speed to 9600bps if that is what the software requires. In
~ the USR, make sure &B1 is set (it should be default); that will limit the
~ USR to a max DCE (modem to modem) speed of 9600bps. The Zoltrix should also
~ follow that limit and that port speed should also be set to 9600bps.
~
~ Again, all of the above is based upon the assumption that, for who knows
~ whatreason, the software wants to communicate with the ports at 9600bps.
I have seen instances where an answering USR modem, when set with
&B1, will fail to keep the DTE speed locked at 9600 bps, but will
behave as the OP describes, and change the DTE rate to something
else after training.
My workaround in the 9600 bps case is to configure the USR modem
NOT to lock its DTE rate (&B0), but to lock the *DCE* rate at 9600.
Here's my cheatsheet (for a Courier; Sportster dipswitches would
be different):
1.) Hook up modem to COM port on PC
2.) Set Hyperterminal settings to:
9600 bps
8 databits
no parity
1 stopbit
no flow control
3.) connect to modem and issue the following AT string:
at&f0s0=1&b0&n6&u6&m4&k0&w
&F0 - no flow control factory template
S0=1 - autoanswer after 1 ring
&B0 - serial port rate follows DCE rate
&N6 - 9600 bps max DCE rate
&U6 - 9600 bps min DCE rate
&M4 - EC with fallback to async
&K0 - no data compression
&W - write to NVRAM
4.) set dip switches on modem to 1-3 up...4 down...5-10 up
5.) power-cycle the modem
Aaron
Hooda Gest
"Aaron Leonard" <Aa...@Cisco.COM> wrote in message
news:0iggivgbbi3gh263b...@4ax.com...
Yes, sorry, I had forgotten about one little glitch in USR modems. On
power-up or when using ATZ for init, it will fall back to whatever DTE speed
was active when the profile was saved. Cure is to save the profile at the
port speed desired.
>
> My workaround in the 9600 bps case is to configure the USR modem
> NOT to lock its DTE rate (&B0), but to lock the *DCE* rate at 9600.
> Here's my cheatsheet (for a Courier; Sportster dipswitches would
> be different):
>
> 1.) Hook up modem to COM port on PC
> 2.) Set Hyperterminal settings to:
> 9600 bps
> 8 databits
> no parity
> 1 stopbit
> no flow control
> 3.) connect to modem and issue the following AT string:
>
> at&f0s0=1&b0&n6&u6&m4&k0&w
> &F0 - no flow control factory template
> S0=1 - autoanswer after 1 ring
> &B0 - serial port rate follows DCE rate
> &N6 - 9600 bps max DCE rate
> &U6 - 9600 bps min DCE rate
> &M4 - EC with fallback to async
> &K0 - no data compression
> &W - write to NVRAM
>
> 4.) set dip switches on modem to 1-3 up...4 down...5-10 up
> 5.) power-cycle the modem
Your saving this while accessing the modem at 9600bps will lock that as the
default port speed.
Might be easier to just disable everything above V.32...
For Courier:
S34=1 S54=128 (disable V.32bis and V.8 mode)
For other USRs:
S27=32 S32=0 (disable V.32bis and V.8 mode)
And save the settings at 9600bps.
Jose V. Gavila
some tricks I was not aware of ;-)!
Best regards,
Jose V. Gavila
--
----------------------------------------------------------------------
73 EB5AGV / EC5AAU - JOSE V. GAVILA
La Canyada - Valencia (SPAIN)
Vintage Radio: http://jvgavila.com
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