User guide

Connection Scenarios for Modem Emulation
266 Chapter 3 Modem Emulation Commands
Connection Scenarios for Modem Emulation
Modem emulation can involve the following types of connection scenarios:
Outgoing Modem Emulation Connection
In an outgoing modem emulation connection, a serial device sends an
ATDx.x.x.x:y command, which triggers the Digi device to establish a
connection to destination IP=x.x.x.x, port=y.
Incoming Modem Emulation Connection
In an incoming modem emulation connection, a device on the network
connects 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
Modem emulation pooling is a combination of Incoming Modem Emulation
Connection and a hunt group. A device on the network connects 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 modem emulation bridge is combination of Outgoing and Incoming
Modem Emulation Connections, in which both serial devices require to talk
to a modem. The first serial device connects to the second device using
ATDx.x.x.x:y, the second device gets a RING and accepts the incoming
connection.
About the Commands in this Chapter
This chapter describes the Digi-specific modem emulation commands that
have been implemented for Digi Connect devices. It is divided into several
sections:
• "Modem Emulation AT Command Set" on page 267. These are
commands to perform actions in a modem-emulation connection.
• "S-Register Definitions" on page 269.
• "Result Codes" on page 271, a description of the result codes for the
commands.
Accepted But Ignored AT Commands
Any other commands not described in this chapter but in the standard AT
command set are accepted but ignored and therefore have no effect. Such
commands are pertinent to actual modems, but not to modem emulation.