connects to the IP Address of the server when an
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.
User Scenario-Diagram B
Workstation
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In Diagram B, two Digi devices will replace modems on both sides of the connection. The initiation of the connection occurs with either of the Digi devices. If both ends are Digi devices, the TCP listening port number is 50001 for port 1. An example of the connection command is ATDT 192.168.25.30:50001. Upon establishing a successful TCP connection, a CONNECT message is sent to the serial port and only then does the Digi device server switch from AT command mode to data mode. After the CONNECT is received, the transmission of data begins. Using the modem escape sequence or dropping DTR on either side terminates the connection.
Modem emulation has the ability to communicate to an infinite number of other devices.
Modem Emulation Cable Signals
Use the following signal assignments to make a cable connecting the Digi device to a serial device.
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DSR (in) |
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44 | Chapter 7 Special Features: Modem Emulation |
