Avocent ESP Serial Hub, Installer/User Manual, Page: 26 / 96

16 ESP Serial Hub Installer/User Guide
• The modem emulation connection method is valid only on an RS-232 port. This method is
exclusive; when it is enabled on a port, no other connection methods can be enabled for
that port.
In any case, a port may be actively open and used by only one method at a time.
Serial port redirection
The serial port redirection connection method uses an ESP serial redirection driver on a host
computer to communicate with the hub. The driver creates a virtual COMM or TTY port interface
within the host’s operating system.
Table 3.1 describes this method’s configurable items for each serial port.
To use the serial port redirection connection method, you must install drivers on the host computer.
See the SuperSerial CD for information. You may also use the ESP-Install program; see
ESP-
Install Program on page 61.
Telnet server
The Telnet server connection method allows a user to make a Telnet connection to a serial port on
the ESP hub and then transmit/receive data using the standard Telnet protocol. This method is also
known as reverse Telnet.
When this method is enabled, the Telnet server within the hub will accept a connection from any
valid remote IP address. There is no filtering of remote addresses. The connection will be accepted
only if the port is not already open and in use by any connection method, including an existing
Telnet session on that port. If the port is currently in use, the connection request will be rejected.
The Telnet session will remain established until the remote client ends the session, the Telnet TCP
socket is broken or the inactivity time-out (if enabled) occurs.
Table 3.1: Serial Port Redirection Configurable Items
Item Description
Enable/
disable
Enables or disables the serial port redirection connection method on the serial port. (See
Exclusivity and restrictions on page 15.)
The default value is enabled.
Serial
buffering
Specifies the length of time accumulated serial data should be buffered before being sent to
the remote server. Valid values are 0-65535 hundredths of a second. A 0 value indicates that
data will be sent as soon as it is available.
For example, a value of 100 indicates that once serial data is received, it will remain buffered
up to 1 second (100 hundredths of a second), at which time all data will be sent.
If the buffer becomes half full, the time is ignored and the data is sent.
The default value is 0 (send immediately).