### 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 specific Digi devices, and they can be named using different directories and prefixes.

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

a-z | The Digi device letter ID. Legal letters are a-z.
01-96 | The port number on the individual Digi device.
s | At the end of a device name indicates a standard device.
m | At the end of a device name indicates a modem device.

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

Device | Path/Name Example
Standard Device | /dev/term/a01s
Modem Device | /dev/term/a01m
Standard Transparent Print Device | /dev/pra01s
Modem Transparent Print Device | /dev/pra01m

#### Standard Device

Example: /dev/term/a01s

A standard Digi device uses 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

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

Device | Path/Name Example
Standard Device | /dev/term/1-01s
Modem Device | /dev/term/1-01m
Standard Transparent Print Device | /dev/pr1-01s
Modem Transparent Print Device | /dev/pr1-01m

When letters are used to identify Digi devices, different Digi devices can use the same letter. To avoid name conflicts Digi devices using the same identification letter are not allowed to use the same port numbers. For example, if two Digi devices 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 Digi devices, each has a unique identification number. There are no name conflicts, and the ports on each 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.

Terminal/Modem Prefix | Device Name
term/ | /dev/term/a01s
tty | /dev/ttya01s
term/digi/tty | /dev/term/digi/ttya01s

Transparent Print Prefix | Device Name
pr | /dev/pra01s
prn/ | /dev/prn/a01s
term/digi/prn | /dev/term/digi/prna01s