~ > 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.
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
