Asynchronous Serial Communications Programmer's Reference Manual (32022-90052)
Chapter 7 145
Programming for PAD, DTC Telnet, Telnet/iX Server, and VT Devices
Virtual Terminal Access on MPE/iX Systems
Virtual Terminal Access on MPE/iX Systems
The Virtual Terminal (VT) service of Network Services (NS) is designed
to allow applications on the MPE/iX remote host to access devices on
local clients as if they were terminals. The VT service on an MPE/iX
host will support connections from MPE/iX, MPE V, PCs, and HP-UX
systems.
For details on the required hardware, software and network
configurations for VT access on MPE/iX systems, as well as more
general information on NS, refer to Getting Started With NS 3000/iX
and NS 3000/iX Operations and Maintenance Reference Manual.
What’s Included
This section includes information on:
• Limits and restrictions that apply to VT connected devices.
• Recommended programming practices for VT support.
General VT Restrictions
Only sessions, not jobs, can be established on the remote host by the
local client; connections to the remote host under job control will be
transparent to the application. This distinction is made for two reasons.
First, some applications handle error recovery differently depending on
whether the application is run from a session or a job. Second, most
FCONTROLs and FDEVICECONTROLs are not supported in the job
environment; they will often be ignored although no error is reported.
VT Programming Considerations
The following file system intrinsics can be used to control devices
connected to an MPE/iX system via VT. For more information about the
following intrinsics, refer to Chapter 8, “Intrinsics Reference,” of this
manual.
FCONTROL
Some FCONTROLs are not supported for use with VT. If a program
uses an unsupported FCONTROL for a VT connected device, the VT
driver will return a CCE condition code, but no device control action
will take place. Any values returned in these calls may not be a true
reflection of device control settings. These FCONTROLs include:
• FCONTROL(10), set line speed.
• FCONTROL(11), set line speed.
• FCONTROL(22), return last read time.