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Serial Port Profiles
Virtual Modem Profile
Overview
Virtual Modem (Vmodem) is a feature of the IOLAN 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 the
IOLAN 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
IOLAN 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).