You can run a TELNET session with a host that uses IBM 3270 model
terminals by using the TN3270 command. The TN3270 command:
o Provides IBM 3270 Information Display System (IDS) terminal
emulation.
o Assigns IBM 3270 functions to your keyboard.
o Assigns IDS functions to specific keys.
During a TN3270 session, you can do the following:
o Record your sessions (Recording Sessions).
o Redefine keys permanently (Key Definition File).
o Redefine keys interactively (DEF KEY Function).
o Troubleshoot problems (TN3270 Troubleshooting).
NOTE
When you run TN3270, you can only have one session. You
cannot have other sessions running simultaneously, as you
can when running normal TELNET sessions.
TELNET can emulate the following IBM 3270 model terminals:
Model Screen Size (Rows x Columns)
IBM 3278 Model 2 24 x 80
IBM 3278 Model 3 32 x 80
IBM 3278 Model 4 43 x 80
IBM 3278 Model 5 27 x 132
1 – Terminal Setup
When you use TELNET and specify IBM 3270 model terminal emulation
(TN3270), the image displayed on your screen depends on the
type of terminal you use (or that your PC is emulating) and the
features you set on it.
o VT200 Series Terminals
To set up a VT200-Series terminal for emulation, follow these
steps:
1. At the Set-up Directory menu, select the keyboard type
that corresponds to the keyboard layout you are using (for
example, North American).
2. At the Display Set-up menu, select the following:
o Interpret controls
o Light text, dark screen
o Cursor (visible)
3. At the General Set-up menu, select the following:
o VT200 or VT100 mode (if VT100 mode, set VT100 ID)
o 7-bit or 8-bit controls
o Multinational/national
o Normal cursor keys
o No new line
4. At the Communications Set-up menu, select the following:
o XOFF at 64 or XOFF at 128
o 8-bit communication line
o 8-bit (any) parity
o No local echo
5. At the Keyboard Set-up menu, select warning bell ON.
At the DCL prompt, enter the following command:
$ SET TERMINAL /INQUIRE
The software determines the terminal's characteristics and
sets the appropriate parameters.
If you select National character mode, enter the following
command:
$ SET TERMINAL /NOEIGHTBIT
o VT100 Series
To set up a VT100-Series terminal for emulation, follow these
steps:
1. Set your terminal to ANSI mode (see the user's guide for
your terminal).
2. Enter the following command at the DCL prompt:
$ SET TERMINAL/INQUIRE
This command causes the terminal to be questioned about
its characteristics. The appropriate parameters for the
terminal are set up according to its response.
TN3270 requires terminal windows that support at least 24
lines and 80 columns.
2 – Starting and Exiting
Start a TN3270 session by using the TN3270 command. You can also
use the TELNET/TERMINAL_TYPE=IBM-3278-n command. The default
terminal type is IBM-3278-2.
You can invoke TN3270 and, without first connecting to a remote
host, enter certain commands that customize the sessions and
display parameters or status. You can also use a command file to
invoke TN3270 and the customization.
The TN3270 command includes several qualifiers that allow you to
specify customized or special files for the following:
o Character-set translation tables file (/CHARACTER_
SET=file) that translates between EBCDIC and the DMCS.
The default file, if set up by your system manager, is
SYS$LIBRARY:TN3270DEF.TBL. If this file does not exist, and
you do not specify a file, TN3270 uses its own translation
table.
o Keyboard definition file (/KEY_DEFINITIONS=file) that you
create as an alternative to the default keyboard layout.
o National Replacement Character Set (NRCS) file (/NATIONAL_
CHARACTERS=n) for which your terminal is configured. The
default for 8-bit terminals is MULTINATIONAL. The default
for 7-bit terminals is US_ASCII.
You can end a TN3270 session (close the connection) in one of the
following ways:
o At the remote host's system prompt, log out.
o At the remote host's system prompt, return to the TN3270
prompt and disconnect the session as follows:
1. At the remote host's system prompt, press the TN3270 escape
character (Ctrl/] is the default).
2. At the TN3270 prompt, enter either the DISCONNECT or the
close command.
Clearing Error Messages
TN3270 displays error messages in a bordered display at the
bottom of your screen. This display overwrites the status display
and remains visible until you clear it. To clear the display,
invoke one of the following functions:
o REFR
o HELP
o SET FIL
o DEF KEY
Recording Sessions
During a TN3270 session, you can record your screen's contents.
The PRINT function directs your screen's contents to either a
file or a spooled printer.
To record your screen's contents, follow these steps:
1. Invoke the PRINT keyboard function, as described in the topic
Keyboard_Functions.
The screen display is recorded in a file in a compressed
state. Null lines (lines with only nulls and attribute
characters) do not appear.
2. Invoke the ENTER function or any function that transmits the
screen contents to the remote host's application, as described
in the topic Keyboard_Functions.
This creates the default output file, TN3270PRINT.LIS. TELNET
does the following:
o Each time you start a TELNET session that runs TN3270, TELNET
opens a new TN3270PRINT.LIS file.
o Each time you use PRINT during a session, TELNET appends new
output from the screen to the end of TN3270PRINT.LIS.
o Each time you use PRINT, if you direct the output to a
printer, TELNET creates a separate entry in the print queue.
o If the printer is spooled, TELNET immediately prints the
output.
You can specify a different file name. To change the name, use
one of the following methods:
o When you start a TN3270 session, use the /PRINTER qualifier,
as shown in the follwing example:
$ TN3270 [ host ] /PRINTER=file
o During a TN3270 session, follow these steps:
1. Use the SET FIL keyboard function, as explained in the
topic Keyboard_Functions.
2. At the prompt for a new file name, enter a name.
If you specify the same name that is already in use,
subsequent PRINT operations direct output to a new version
of the same file.
3. Use the NEW LINE keyboard function, as explained in the
topic Keyboard_Functions.
Locked Keyboards
If your keyboard locks, the terminal bell rings, and the status
line displays the following information:
Inhib
To unlock the keyboard, press the KP0 key to invoke the RESET
function. (KP0 refers to the zero (0) key in the application
keypad on the right hand side of the keyboard.)
Do not use the following functions when the cursor is in a
protected field (a field that does not accept user input):
o DELETE
o DUP
o ER EOF
o FM
o Any graphic character