Serial Port Profiles
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Terminal Server User Guide, Version 3.3
Virtual Modem Profile
Overview
Virtual Modem
(Vmodem) is a feature of the Terminal Server that provides a modem interface to a
serial device. It will respond to AT commands and provide signals in the same way that a serially
attached modem would. This feature is typically used when you are replacing dial-up modems with
an Terminal Server in order to provide Ethernet network connectivity.
Functionality
The serial port will behave in exactly the same fashion as it would if it were connected to a modem.
Using AT commands, it can configure the modem and the issue a dial-out request (ATTD). The
Terminal Server will then translate the dial request into a TCP connection and data will be begin to
flow in both directions. The connection can be terminated by ’hanging’ up the phone line.
You can also manually start a connection by typing
ATD<ip_address>,<port_number>
and end
the connection by typing
+++ATH
. The
ip_address
can be in IPv4 or IPv6 formats and is the IP
address of the receiver. For example,
ATD123.34.23.43,10001
or you can use
ATD12303402304310001
, without any punctuation (although you do need to add zeros where there
are not three digits presents, so that the IP address is 12 digits long).
Act as Tunnel
Client
The Terminal Server will initiate the connection the Tunnel Server.
Default:
Disabled
Host Name
A preconfigured host name that is associated with the IP address of the Tunnel
Server.
TCP Port
The TCP port that the Terminal Server will use to connect to the Tunnel
Server.
Default:
10000+serial port number; so serial port 5 is 10005.
