Using NS3000/iX Network Services (36920-90008)

Chapter 2 41

Virtual Terminal

Reverse Virtual Terminal

The Reverse Virtual Terminal (Reverse VT) service allows an

application program to receive information from and send information

to terminals located on other systems. All the systems involved must be

connected via NS 3000 connections (either NS 3000/V or NS 3000/iX).

The Reverse VT service must be initiated from the system on which the

application resides.

Two important points for Reverse VT are as follows:

• Reverse VT is supported for terminal type 10 only;

• The terminal must be available in order to be opened successfully by

the application. That is, no one can be logged on and no other

application can be accessing the terminal. Pressing

[Return], for

example, will make a terminal unavailable (the system is waiting for

a logon attempt) until the logon timer expires.

To gain access to a remote terminal via Reverse VT, you can specify the

VTERM option in the FILE command, which designates the terminal as a

remote device. Or the application program itself may include the VTERM

option in the device parameter of the FOPEN intrinsic which opens the

connection to the device. (For the syntax of the FILE command and the

FOPEN intrinsic, when used to access remote ﬁles and devices, see the

Remote File Access chapter of this manual.)

The format for the ﬁle equation is either:

FILE X=X:envID;DEV=#ldev;VTERM **8-character environment ID**

FILE X=X;DEV=envID#ldev;VTERM **8-character environment ID**

The format for the FOPEN device parameter is:

#ldev;VTERM [Return] **must be terminated by ASCII value

for carriage return**

In the FOPEN call, the location of the device may be speciﬁed either in

the formaldesignator parameter (X:envID) or in the device parameter

(envID#ldev;VTERM

[Return]). If the FOPEN call indicates the location of

the ﬁle, you can specify the VTERM option in a ﬁle equation issued

directly on the remote terminal’s node:

ENV1#FILE X;DEV=# ldev;VTERM

The ldev parameter is either the device class name or the logical device

number of the remote terminal. If you specify a device class name

rather than the logical device number of a terminal, the ﬁrst available

terminal in the device class table will be used.