User`s guide

Chapter 8 Special Features: Modem Emulation 69
Incoming Modem Emulation Connection
A device on the network telnets to port 50001 (50000+1 = 1st serial port).
This incoming connection triggers the Digi device to generate a RING on
the serial port. The device attached to the serial port will answer the RING
and the connection is established.
Modem Emulation Pooling
This is a combination of Incoming Modem Emulation Connection and a
hunt group. A device on the network telnets to port 50000. The Digi device
checks if a serial port configured for modem emulation is available. If so, it
connects to the port, otherwise returns an error.
Modem Emulation Bridge
A combination of Outgoing and Incoming Modem Emulation Connections,
in which both serial devices require to talk to a modem. The first serial
device telnets to the second device using ATDx.x.x.x:y, the second device
gets a RING and accepts the incoming telnet connection.
Originating, Answering, and Disconnecting Calls
In the following table, an application requests a TCP session with the Digi
device. The table displays the responses of the Digi device and application
as they negotiate a TCP connection.
In the following table, the Digi device receives a request for a connection.
Originating Calls
To send data to a Digi device, enter the following information for your
application replacing the telephone number with the Digi device’s IP
address and TCP port number. Enter the following command:
Application AT
Command
Digi Device Response Notes
AT&F OK.
AT command request to restore defaults to factory set-
tings-Digi device responds OK.
ATDT ipaddress:TCPport#
Receives request to start a
TCP session. CONNECT
115200.
Request to start TCP session with IP address and TCP
port number of the Digi device-which then starts a TCP
session
<P>+++<P> OK
Escape sequence is sent <P> is Pause in seconds with
“+++” being the escape sequence in ASCII characters -
Digi device switches from AT command to data mode
ATH NO CARRIER response sent
Disconnect AT command is sent-Digi device responds
with NO CARRIER
AT Command Digi Device Response Notes
RING The Digi device sends a Call Notification
ATA (or ATS0=n) CONNECT 115200
Manual (ATA) or Auto Answer (ATS0=n) response-the
Digi device sends a CONNECT message when the
TCP session is started
NO CARRIER
The Digi device sends a NO CARRIER message when
the remote disconnects