RealPort Devices

The RealPort installation creates four different devices for each port.

• Standard device
• Modem device
• Standard transparent print device
• Modem transparent print device.

Device Name Format

RealPort devices can be named using either letters or numbers to identify the PortServers, and they can be named using different directories and prefixes.

By default, the devices are named according to the following conventions:

Here are examples of the devices for the first port of a PortServer with the identification letter "a":

Standard Device

Example: /dev/term/a01s

A standard PortServer device uses a the letter "s" at the end of their names. The default handshake method is XON/XOFF. Data Carrier Detect (DCD) need not be present to open the device.

Note: Once a connection is established and DCD becomes active, standard devices behave in the same way as modem devices--subsequent loss of the Data Carrier Detect signal will cause active processes on the port to be killed and the user will be automatically logged off.

Modem Device

Example: /dev/term/a01m

PortServer modem devices use the letter "m" at the end of their names. They are sometimes referred to as "dial-in" devices.

Modem devices are traditional Unix ports with modem control. They require Data Carrier Detect to be high before they will operate. RTS/CTS handshaking is enabled by default. When used with a modem, the ports will wait for DCD before sending out the login prompt.

When used with a terminal or other device, it is usually wise to wire the Digi DCD signal to the terminal's Data Terminal Ready (DTR) line. When the terminal is turned on, the system outputs a login prompt. When the terminal is turned off, any associated jobs are killed, and the user is logged out.

Transparent Print Devices

Examples: /dev/pra01s and /dev/pra01m

The transparent print devices can be used with auxiliary printer ports on terminals. Output directed to a pr device goes out the auxiliary port of a terminal while you continue to use the terminal normally.

Use pra01s if the terminal device is a01s (standard device); use pra01m if the terminal device is a01m (modem device).

Alternate Naming Conventions

Using the realport_config program it is possible to change the naming conventions for RealPort devices.

Instead of letters, PortServer numbers can be used to identify the PortServer in the device names. Here are examples of the devices for the first port of a PortServer with the identification number "1":

When letters are used to identify PortServers, different PortServers can use the same letter. To avoid name conflicts PortServers using the same identification letter are not allowed to use the same port numbers. For example, if two PortServers share the letter "a", the first might have ports "a01" to "a16" and the second ports "a17" to "a32".

When numbers are used to identify PortServers, each PortServer has a unique identification number. There are no name conflicts, and the ports on each PortServer are always numbered starting at "01".

You can also change the directory and prefix of the device names. The default prefix for terminal and modem devices is "term/", and for transparent print devices it is "pr". Here are examples that show how the device names change with different prefixes.