Configuring Systems for Terminals, Printers, and Other Serial Devices (32022-90051)
172 Chapter9
Describing Asynchronous Devices
How MPE/iX Identifies Devices
How MPE/iX Identifies Devices
Asynchronous devices (terminals, printers, plotters, etc.) are located
and communicated with in two ways:
• Through the device’s logical device (ldev) number.
• Through the physical path from the HP 3000 to the asynchronous
device.
Logical Device Numbers
The ldev number is a value that the MPE/iX operating system uses to
recognize attached devices. Terminals attached to Datacommunications
and Terminal Controllers (DTCs), managed by an HP 3000 host, are
configured with nailed ldev numbers. Terminals attached to DTCs,
managed by an OpenView Windows Workstation, can be configured to
have either nailed ldev numbers or non-nailed ldev numbers on the
host systems to which they have access. Logical device numbers are
associated with nailed devices during configuration.
A nailed device has a permanently assigned ldev number. A non-nailed
device has an ldev number associated with it after a session is
requested.
A terminal connected through a DTC to multiple HP 3000 computers
can have nailed connections on more than one host system.
Alternatively, a terminal can have a nailed connection on one host
system and a non-nailed connection on another, or it can be configured
to have non-nailed connections on all of the systems to which it has
access.
Non-Nailed Devices
A non-nailed device is able to establish a connection to the HP 3000
computer but has no permanently assigned ldev number in the
NMMGR configuration file. The user of a terminal connected as a
non-nailed device can establish a session provided a connection is
available and the host configuration specifies a device profile matching
the characteristics of the device requesting the connection.
When the user logs onto the host, an ldev number is assigned from a
pool of available ldev numbers. When the connection is ended (the user
logs off), the ldev number is returned to the pool of ldev numbers and
becomes available for use by a different device. It is possible to
configure non-nailed devices only when PC-based management is used.