### RealPort Devices

The RealPort installation creates three different devices for each port in the /dev directory.

- Standard device
- Modem device
- Transparent print device

#### Device Name Format

The devices are named according to the following conventions:

aa-zz | The Digi device letter ID.
01-64 | The port number on the individual Digi device.

Following are examples of the devices for the first port of a PortServer with the identification letters "aa":

Device | Path Name Example
Standard Device | /dev/cuaa01
Modem Device | /dev/ttyaa01
Standard Transparent Print Device | /dev/praa01

#### Standard Device

Example: /dev/cuaa01

A standard Digi device begins with the prefix "cua". The default handshake method is XON/XOFF. Data Carrier Detect (DCD) need not be present to open the device.

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/ttyaa01

Digi modem devices begin with the prefix "tty". 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 Device

Example: /dev/praa01

The transparent print device 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.