Procedure: There are two ways to configure the serial port for use with terminals.
A. Web Interface - see section on Configuring Ports for Terminals: Web Interface below.
B. Command Line - see section on Configuring Ports for Terminals: Command Line below.
NOTE: The PortServer or PortServer II units are not supported by the Web Interface and must be configured via the Command Line.  

Configuring Ports for Terminals: Web Interface
1. Access the web interface by entering the Digi One Device Server or PortServer TS  IP Address in a browser’s URL window.
  

2. Log in to the Digi One Device Server or PortServer TS  as root.  The default password is dbps. 
3. From the main menu, choose Configure > Ports.
   

4. To configure a port, do the following:
    a. Choose the port from the port column.
    b. Ensure that the Device type is set to Terminal.
    c. Make changes to the port settings (baud rate, parity, etc.) as required.   Use the online help for information.
    d. If you want to apply this configuration to multiple ports, choose Clone, and select the ports you want to copy this
        configuration to.  Click Continue.
    e. Choose Submit.
5. To return to the main Ports menu, choose Ports from the Menu again.
6. The port has now been configured for use with a terminal.

Configuring Ports for Terminals: Command Line
This procedure assumes the following:
A. That you are logged in as root
B. That you know the attributes, such as baud rate, parity, etc. required for use with the terminal that will be connected to this
     port.

1. Supply a set port command that specifies the following from the command prompt:
    #> set ports range=range dev=term sess=num-of-sess
    NOTE: where range is a port or range of ports and num-of-sess is the number of simultaneous sessions the port user
    can maintain

2. Supply a set line command that specifies the following from the command prompt:
    #> set line range=range baud=bps csize=characters parity=parity stopb=numbits
    NOTE: The set line configuration must match the settings of the attached terminal where:
    a.  range is a port or range of ports.
    b.  bps is the line speed.
    c.  characters is the character size.
    d.  parity is the parity scheme to use on this line.
    e.  num-bits is the number of stop bits to use.

3. If your terminal is configured for hardware flow control, supply a set flow command that specifies the following from the
    command prompt:
    #> set flow range=range ixoff=off ixon=off cts=on rts=on
    NOTE: software flow control is the default, so a set flow command is not required in that case.
    NOTE: You may need to use additional set flow command fields, depending on the flow control scheme required by your
    terminal. See the set flow command in the Digi Device/Terminal Server Command Reference for more information.

Example:
In this example, port 1 and 2 are configured for connection to terminals using hardware flow control. The connection uses default for character size (8 bits), parity (no parity), and stop bits (1).

#> set ports range=1-2 sess=3 dev=term termtype=wy60
#> set line range=1-2 baud=19200
#> set flow range=1-2 ixon=off ixoff=off rts=on cts=on

Cabling:
Make sure you are using the proper cabling for connecting your Terminal to the Digi Device/Terminal Server.
http://supportold.digi.com/support/manuals/psts/90000253_D.pdf