User guide

Common User Scenarios for Modem Emulation
264 Chapter 3 Modem Emulation Commands
Common User Scenarios for Modem Emulation
The Digi device in modem emulation mode allows for the easy replacement
of modems in almost any environment where there is a LAN or WAN.
In Diagram A, the Digi device replaces a modem connected to a
workstation running an application. The Digi device allows for the use of
software applications without modification by responding to all the AT
commands configured in the workstation application. The Digi device
connects to the IP Address of the server when an ATDT command is
issued, for example:
ATDT ipaddress:port (ATDT 192.168.25.5:50001)
command is issued. Once the remote device establishes the TCP
connection, a CONNECT message is sent to the serial port and only then
does the Digi device switch from AT command mode to data mode. Using
the modem escape sequence or dropping DTR on either side terminates
the connection. A DISCONNECT message will be sent to the application if
the remote side closes the TCP connection.
Server
192.168.25.5
Workstation
Serial cable
Ethernet
Digi device
User Scenario - Diagram A
D
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