Asynchronous Serial Communications Programmer's Reference Manual (32022-90052)

Chapter 7 135
Programming for PAD, DTC Telnet, Telnet/iX Server, and VT Devices
PAD Access to MPE/iX Systems
Programmatic Access. Terminals and serial printers can be accessed
programmatically if they are connected to a private PAD and configured
as nailed devices on the MPE/iX host on which the application is
running. To open a device programmatically you use the FOPEN or
HPFOPEN intrinsic with the
device option specifying the ldev
number or device class that was associated with the remote device
through the NMMGR configuration.
General PAD Restrictions
Some basic limitations apply to the way transmission occurs and to the
operations that are supported over PAD connections:
• It is necessary to press
[Return] to forward data from the PAD across
the network to the DTC even if the byte count specified in the read is
reached.
• Some special character sequences, such as subsystem break (
[CTRL]Y
by default), must also be forwarded with a [Return].
• You cannot use a PAD terminal as a console.
• Use of customized terminal and printer types files is not supported
over PAD.
• You cannot use the :STARTSESS command with ldevs that allow
PAD device connections.
• Typeahead mode is not supported over PAD on versions prior to
release 4.5, C.45.00.
• Binary mode transfers are not supported between a PAD terminal
and a MPE/iX or HP-UX host on versions prior to release 4.5,
C.45.00.
• User Block Mode and HP Block Mode applications are not supported
on PAD devices.
• Parity generation and checking is not supported programmatically
over PAD.
• The line deletion response (
[CTRL]X echo characters, !!! by default)
cannot be enabled or disabled programmatically over PAD (though
some PADs allow you to define line deletion characters locally).
• PAD printers cannot be shared by more than one host.
PAD Programming Considerations
Most file system intrinsics can be used to control devices connected to
PADs as if the devices were locally connected. Both the FCONTROL
and FDEVICECONTROL intrinsics are supported for PAD device
control. In most cases the device control calls work as normal.