Configuring Telnet server for 3270 full-screen mode

 

Telnet client users can sign on and run 5250 full-screen applications using 3270 full-screen mode.

The system negotiates 3270 full-screen support with any Telnet client application that supports 3270 full-screen applications, rather than 5250 full-screen applications. An example of a system that negotiates 3270 full-screen support is the IBM® System z™ family.

Telnet 5250 (TN5250) delivers the data stream between the two systems as EBCDIC. Because the 3270 data streams are translated into 5250 data streams, the workstation devices operate as a remote 5251 display to the system and application programs.

After you have completed the general configuration of the Telnet server, there are a few additional steps to enable system support for 3270 full-screen mode. Full-screen mode is a block mode as opposed to a line mode. Line mode is when data transmits one line at a time, whereas block or full-screen mode transmits the whole screen at one time.

Complete the following tasks to configure the Telnet server for 3270 full-screen mode:

  1. Check the QKBDTYPE system value. Refer to Checking the QKBDTYPE system value

  2. Set the default keyboard mapping. Refer to Setting the default keyboard mapping

  3. Change a keyboard map. Refer to Changing a keyboard map

  4. Change message queue. Refer to Changing message queue

 

Checking the QKBDTYPE system value

When the Telnet server automatically creates virtual display devices, it uses the QKBDTYPE system value to determine the keyboard type for the virtual device.

If the initial creation of the virtual device fails by using the QKBDTYPE system value, the Telnet server uses the keyboard value USB to try to create the device. If the second attempt to create the virtual display device fails using the value of USB, then a message (CPF87D7) is sent to the system operator message queue. This message indicates that the system cannot automatically select the virtual device.

 

Setting the default keyboard mapping

A 3270 display station connected to a System i™ model using Telnet appears to be a 5251 display station to a System i platform. The 3270 display station keyboard has a 5251-equivalent keyboard map associated with it. The 5251-equivalent keyboard map allows the 3270 display station keyboard to complete 5251-equivalent functions on the system.

When a Telnet client system user first signs on in 3270 full-screen mode, the system automatically assigns the default keyboard map to the user's 3277, 3278, or 3279 keyboard. Avoid this by including a user-defined keyboard map in the user's profile sign-on procedure. This supplies the mapping needed for the 3270 keyboards to do most of the same functions as their 5250-equivalent keyboards do.

 

Displaying a keyboard map

You can use the Display Keyboard Map (DSPKBDMAP) command to see the current keyboard mapping. Another method is to use option 6 (Display 3270 keyboard map) on the Configure TCP/IP Telnet menu, while your terminal is in 3270 emulation mode.

Changing a keyboard map

Use the Change Keyboard Map (CHGKBDMAP) command if you want to make minor changes to the default keyboard map. This command is available from the Configure TCP/IP Telnet menu as option 7 (Change 3270 keyboard map).

If you want to set a new keyboard map, use the Set Keyboard Map (SETKBDMAP) command. This command is option 7 (Change 3270 keyboard map) on the Configure TCP/IP Telnet menu. The key assignments that you specify are in effect until you use these commands again to specify new key assignments or until you sign off.

The difference between CHGKBDMAP and SETKBDMAP is that, with SETKBDMAP, the system applies the defaults and then the changes in the SETKBDMAP are applied. With CHGKBDMAP, the system applies defaults plus any changes that you have previously made during this session, and then the changes in the CHGKBDMAP are applied.

 

Changing message queue

A message queue is like a mail box for messages. The system has several message queues that hold messages that provide helpful information when finding and reporting problems. When your workstation message queue is in break mode, messages appear on the 3270 device exactly as they appear on the 5250 display. To receive messages in break mode, specify *BREAK on the change message queue (CHGMSGQ) command. When your workstation is not in break mode, you receive the following message: A message has arrived on a message queue.

To retrieve this message and continue using the workstation, follow these steps:

  1. Press the function key assigned to the help function, or the function key that is assigned to the error reset function.

  2. Enter the Display Message (DSPMSG) command or the function key that is assigned to the system request function followed by option 4 (Display Message) to view the waiting message.

  3. Set the workstation message queue to break mode to see the messages as they arrive.

 

Resetting the display's input-inhibited light

When using a System i model from a 5250-type terminal, pressing certain keys in certain situations causes input to be inhibited. When this occurs, the 5250 terminal displays an input-inhibited light.

Two asterisks shown in the lower-right corner of the display indicate the input-inhibited light. When the keyboard is inhibited, any keys mapped to the i5/OS® function keys are ignored.

To reset the keyboard, press the Enter key, or press the key mapped to the Reset key.

  • Supported 3270 terminal types
    The topic describes the capabilities of the 3270 devices that Telnet supports. Make sure that your Telnet client 3270 is negotiating one of the supported 3270 terminal types.

 

Parent topic:

i5/OS supported emulation types

Related concepts
3270 Telnet client sessions 3270 keyboard mapping for Telnet servers

Related reference
Supported 3270 terminal types