Digi WAN 3G User Manual page 112

TCP Sockets profile
The TCP Sockets profile allows serial devices to communicate over a TCP network. The TCP
Server allows other network devices to initiate a TCP connection to the serial device attached to
the serial port of the Digi device.
Automatic TCP connections (autoconnection)
The TCP Client allows the Digi device to automatically establish a TCP connection to an
application or a network, known as autoconnection. Autoconnection is enabled through the TCP
Sockets profile's setting labeled Automatically establish TCP connections.
When the TCP Sockets profile is set, the DTR flow-control signal indicates when a
Note
TCP socket connection has been established. This information can be useful in
monitoring the serial line and using it as a flow-control mechanism to determine when
the Digi device is connected to a remote device with which communication is being
established. This mechanism can be combined with using the DCD signal to close the
connection and the DSR signal to do RCI over serial. Together, these signals can be
used to make the Digi device auto connect to many devices, deterministically, on the
network.
RFC 2217 support
Digi devices support RFC 2217, an extension of the Telnet protocol used to access serial devices
over the network. RFC 2217 implementations enable applications to set the parameters of remote
serial ports (baud rate, flow control, etc.), detect line signal changes, as well as receive and
transmit data. The configuration information provided in this section applies to Digi device
functioning as RFC 2217 servers.
If using the RFC 2217 protocol, do not modify the port settings from the defaults. If the port
settings have been changed, restore the factory default settings (see "Restore a device
configuration to factory defaults" on page 182). No additional configuration is required.
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