Lantronix ETS, Справочное руководство

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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