Lantronix ETS Reference Manual - 5.2   Modems

Modems

Ports

5-6

Each virtual port is created with a default set of characteristics. The Set/Define Port commands (starting 

with Define Port Access on page 12-27) can be used to customize a virtual port during the Telnet/Rlogin 

session; however, these customizations cannot be saved. The port reverts to the default set of characteristics 

once the session is closed.

To make configurations that apply to all virtual ports (all future Telnet/Rlogin connections), use Define Port 

commands and specify zero as the port number. All port settings can be configured for virtual ports except 

those that don’t make sense for virtual ports, (i.e., Autobaud, Dedicated, Dialback, DSRLogout, DTRWait, 

Modem Control, and SLIP).

For example, the command in Figure 5-17 makes all ports process the Break key locally rather than passing 

it on to the remote service. 

Figure 5-17:  Configuring Virtual Ports

Note:

Virtual ports cannot be configured with Set commands, they can only be 

configured with Define commands.

Because NCP and Telnet remote console sessions are considered virtual logins, configurations made with 

Define Port 0 commands will apply to them as well. Virtual port settings are often used to provide local 

switches to network logins, as they typically do not have a Break key to use after the connection is made.

Note:

Use the List Port command to view virtual port characteristics.

5.2   Modems

Modems are usually connected to data equipment (such as terminals or servers) with a 25 pin DB-25 

connector that allows the equipment to see all the signals the modem provides. These signals include Ring 

(RI), Carrier Detect (CD), and Data Set Ready (DSR). 

Although modems are sometimes difficult to set up, the following points should help you connect one to 

your ETS. Refer to the cable pinouts in your Installation Guide for more details as you read these 

instructions. Keep in mind two things:

The special handling for modem connections is only done if the port in question has Modem Control 

enabled. See the Define Port Modem Control command for details.

The way the ETS handles modem ports is rather simple and straightforward. Most modem problems are 

caused by cabling mistakes or by an incorrect modem configuration. 

5.2.1   Modem Basics

When Modem Control is enabled on a port, the ETS uses the DSR input signal on the serial port to decide 

when there is a valid modem connection and the Data Transmit Ready (DTR) output line to signal the 

modem that a connection is possible or acceptable. The attached modem may not be using these signals as 

the ETS expects, however. 

For a sample incoming call, the signal sequence might be:

Local>> DEFINE PORT 0 LOCAL SWITCH ^F