Configuring Systems for Terminals, Printers, and Other Serial Devices (32022-90051)

Chapter 9 173
Describing Asynchronous Devices
How MPE/iX Identifies Devices
Nailed Devices
A nailed device is permanently assigned an ldev number through the
NMMGR configuration of the HP 3000 computer. Any time a connection
exists between a computer and one of its nailed devices, the same ldev
number will belong to that device. Only nailed devices can be accessed
programmatically. All printers must be nailed, as must any device that
will be accessed programmatically. Devices with permanently assigned
ldev numbers keep the same ldev number unless that number is
modified through NMMGR and the host is restarted. All devices are
nailed when host-based network management is used.
NOTE
If two or more systems have access to the same nailed device,
contention for that device might exist. Only one system can access a
nailed device at any time. For example, if system A accesses the nailed
device, system B will not be able to access the nailed device at the same
time. The nailed device is being used by system A and is probably not
broken, even though it can’t be reached.
An ldev number can be assigned to any asynchronous device, including
the following:
The system console
Printers, Terminals, and Plotters
Other serial devices
System Console
The system console is always connected through the access port on the
HP 3000 Series 900 computer. The system console’s ldev number is
assigned during system initialization and remains constant unless it is
modified through the SYSGEN utility and the host is restarted.
Printer
Printers are assigned ldev numbers during configuration making them
nailed devices. Each printer keeps the same ldev number unless that
number is modified through NMMGR and the host is restarted.
Terminals
Usually, many terminals are connected to a DTC. Some terminals can
have permanent ldev numbers assigned during NMMGR configuration.
Other terminals might not have permanent ldev numbers assigned
(non-nailed). Instead, these terminals will use an ldev number from a
pool of available ldev numbers. Non-nailed devices can be configured if
PC-based network management is used. Refer to “Nailed Devices” and
“Non-Nailed Devices” earlier in this chapter for more information.