3270/SNA Option Guide

Introduction

This introduction describes the purpose and organization of this guide and how you should use it.

Purpose of This Guide

The VINES® 3270/SNA Option Guide explains how to perform all the tasks needed to make 3270/SNA available to users on the network. It provides detailed information on all 3270/SNA features for users with various levels of experience.

The 3270/SNA option enables PC users on a VINES network to emulate 327x terminals using Systems Network Architecture (SNA).

Who Should Read This Guide

This guide presents information for novice users, technical users, installers, system administrators, and knowledgeable network administrators.

Novice users should have some experience using a PC and a 327x-type terminal. Technical users should have previous experience in an SNA environment.

Installers should be familiar with serial communications and Token-Ring hardware, and know the requirements of the site at which the option is being installed.

System administrators should know the requirements of their users. They should be familiar with the PC environment, and have easy access to a systems programmer or administrator in the host environment.

Knowledgeable network administrators should have a detailed understanding of the Synchronous Data Link Control (SDLC) protocol, Token-Ring, and SNA.

How to Use This Guide

This guide is organized so that all readers can easily find the information pertinent to them.

Chapter 1 and Chapter 2 describe using 3270/SNA features. Chapter 1 should be made available to all users. Chapter 2 should be given to users at the administrator's discretion. System or network administrators should read both these chapters before configuring the option. By doing so, they will gain a better understanding of how to set up the option to meet their users' needs, and how to respond to users' questions.

Chapter 3, Chapter 4, and Chapter 5 should be read by installers and system and network administrators to learn how to install and configure the hardware and software for this option. Once the option is running successfully, these chapters will serve as a reference.

Appendix A, Appendix B, and Appendix C should be read by system and network administrators to learn how to interpret SNA error messages, obtain a technical overview of 3270/SNA services, and use SNATRACE. These appendixes assume a detailed understanding of SNA on the part of the reader.

Some information on 3270/SNA is relevant for users and administrators. To maintain the modular structure of this guide, that information is repeated for both audiences.

Quick Overview of the Contents

Information covered by this guide is summarized below:

Chapter 1 - Using 3270/SNA provides users at all levels with information on the features available in 3270/SNA. After a general discussion of terminal emulation, details are provided on connecting to a host, beginning and ending host sessions, and using the 3270/SNA menus and screens.

Chapter 2 - Using 3270/SNA Advanced Features provides experienced users with information on capturing print data on disk, customizing the PC keyboard, entering the terminal emulation program from the DOS command line, making terminal emulation software resident on the PC, and using adapter files to set up the printer and customize PC display colors.

Chapter 3 - Installing the 3270/SNA Option presents an overview of how a 3270/SNA service works, then details the procedures for installing hardware and software, assigning serial communications lines, and configuring Token-Ring cards for SNA.

Chapter 4 - Planning a 3270/SNA Service discusses planning the station characteristics and the LU characteristics of the 3270/SNA service.

Chapter 5 - Managing a 3270/SNA Service discusses creating and managing a 3270/SNA service, making the service available to users, and changing configuration information.

Appendix A - Error Messages, written for VINES and host administrators, lists the error messages that can appear during emulation, with possible causes and corrective actions.

Appendix B - Technical Description lists the SNA devices and requests that the service supports.

Appendix C - SNATRACE describes how to use SNATRACE, the 3270/SNA trace tool.

Using 3270/FTS describes the software that transfers files between an IBM® mainframe and an IBM, or compatible, PC.

Related Documentation

Other manuals provide information about a VINES network. You may want to refer to one or more of the following documents:

VINES Server Installation Guide - Provides complete information on installing and starting a VINES server, and explains how to set up PCs to run on the network.

Planning a Banyan Network - Discusses the concepts behind creating and managing a VINES network. Presents guidelines for determining a site's individual needs, and provides checklists of management tasks.

Managing Users and StreetTalk - Explains how to manage users and resources in a VINES network. Provides a step-by-step procedure for each management task.

VINES User's Guide for Windows - Provides users with complete instructions for logging in and using VINES functions.

VINES Option Guides - Separate guides are available that provide information on installing, managing, and using VINES options.

If you need more conceptual information on Token-Ring cards and related subjects, refer to the following documents from IBM:

IBM Token-Ring Network Introduction and Planning Guide

IBM Token-Ring Network Architecture Reference

IBM Token-Ring Network PC Adapter Technical Reference

Chapter 1 - Using the 3270/SNA Option

The 3270/SNA option allows you to use your PC as a terminal connected to an IBM or other host computer that uses Systems Network Architecture (SNA). Once a connection is established, you can use any of the resources available on the host.

This chapter discusses the following topics:

	What is terminal emulation?
	Connecting to a host computer.
	Using basic 3270/SNA terminal emulation functions:

- Beginning a host session

- The emulation screen status line

- Using the Command Menu

- Viewing keyboard definitions

- Managing multiple sessions

- Exiting from emulation

- Returning to emulation

Using a 3270/PC

Chapter 2 provides complete details of other 3270/SNA features that are available for users who have some experience using SNA. These features include: managing 3270/SNA programs in PC memory, customizing the keyboard or PC display adapter, capturing print data, and using the 3270 command to enter 3270/SNA emulation.

System administrators should read through this chapter and Chapter 2 to get a complete view of what features are available to their users.

What Is Terminal Emulation?

Computer terminals let users exchange information with a mainframe computer. The terminal's keyboard accepts input from the user, and its screen displays input and output from the mainframe, also called a host computer.

The 3270/SNA Terminal Emulation option allows a PC to interact with the host. Terminal emulation happens when a device that is not a terminal (such as a PC) runs a program that enables it to behave like a terminal and interact with a host computer.

When you use 3270/SNA, you connect to a host computer that uses Systems Network Architecture-a set of rules that governs the interaction between the host computer and devices such as terminals. 3270/SNA Terminal Emulation connects the host computer to the network. Your PC emulates an IBM 327x Information Display Unit, a terminal used with an IBM or compatible computer. You can use the application programs on the mainframe as if you were at a terminal connected to that mainframe.

Your administrator must set up 3270/SNA terminal emulation on your network before you can use it. If you have a problem when you try to use 3270/SNA terminal emulation, talk to your administrator.

Before you use 3270/SNA Terminal Emulation, you should understand two important terms related to terminal emulation: logical unit (LU) and session.

A logical unit is a peripheral piece of hardware with which a mainframe computer can communicate, such as a display terminal or a printer. When you enter 3270/SNA terminal emulation, your PC attaches to the mainframe as one or more LUs. You can use from one to four display LUs simultaneously, or from one to three display LUs and a printer LU. A display LU is a terminal that displays information on its screen. When your PC acts as a printer LU, you can print output from the emulation session to a PC port (either a locally attached printer or a network print queue), or capture it on disk. (See Chapter 2 for details.)

A session occurs when your PC interacts with any program on the host computer. This interaction occurs after a PC becomes an active device on the host computer. While you are using a host application, you are engaged in a session.

Connecting to a Host Computer

Making a connection to a host computer is easy-select the name that identifies the host computer to which you want to connect. When you select a connection name, the VINES 3270/SNA service makes the connection for you.

Note that if you have a 3270/PC, you can load a special program to use the special keys on your keyboard. For more information, see the last section in this chapter, "Using a 3270/PC."

To begin terminal emulation, select the option Communications with Other Computers at the VINES Main Menu. (To save a step, type the HOSTS command from DOS.) The Select a Connection menu appears, as shown in Figure 1-1.

The bottom portion of the screen lists all of the connection names you can select.

To select a connection, perform these steps:

1. Choose the function, START a Connection.

2. Use the arrow keys to select a connection name. Your administrator will tell you which one to use. If a connection is temporarily unavailable, it does not appear on the screen.

When the logo screen for 3270/SNA Terminal Emulation appears, you are connected to the appropriate IBM host computer using 3270/SNA Terminal Emulation.

Next, the 3270/SNA screen appears. It can be blank or display a message if the host sends one. It always displays a highlighted line at the bottom of the screen, called the status line. This line provides information about the status of your session. See "The Emulation Screen Status Line" for details.

3270/SNA terminal emulation attaches your PC to one or more logical units. The sections that follow discuss what happens and what you can do, after the connection is made.

Beginning a Host Session

Once the 3270/SNA emulation screen and status line appear, your PC is engaged in a session with the host. You now should log on to the host computer as directed by your system administrator.

When you enter terminal emulation and log on to the host computer, you can use any host application from your PC as if it were a 3270 terminal. For instructions on using an application, refer to the documentation for that application.

From the 3270/SNA emulation screen, you can use the Command Menu, which allows you to examine the keys on the PC keyboard that perform the functions of the 3270 keys, return to the host application, or exit to the DOS prompt. You access this menu by pressing <F3>. Details on this menu are provided later on.

The Emulation Screen Status Line

The status line always displays on the last line of the 3270/SNA emulation screen. As conditions change, the information on the status line changes. Status information displays in either graphic characters or text, depending on how your PC is set up. Figure 1-2 shows a sample status line.

The status line displays information about the following elements of a session:

	On-line Status
	Connection Status
	Keyboard Status
	Printer Status
	Character Mode
	Current LU Status
	Status Messages

While the system is functioning normally, the keyboard status is the most important element. However, if something disrupts communications between your PC and the host system, then all of the status information is important and you need to examine it carefully.

A descripton of each condition and a list of the text or symbols that can appear are in the sections that follow.

On-Line Status

On-line status indicates the active link between the VINES server and the host computer. Table 1-1 shows what the on-line status messages mean.

Connection Status

The connection status indicates the activation level of your PC as an SNA logical unit. Table 1-2 shows the connection status messages and symbols, and what they mean.

Keyboard Status

Keyboard status indicates if the keyboard is locked, and why. Locking occurs as part of the normal communication with the host computer. It can occur if you enter an illegal keystroke or if the host computer encounters protocol errors. To unlock most of the keyboard lock conditions, press the <RESET> key.

Table 1-3 shows the keyboard status messages and symbols, and what they mean. Unless otherwise indicated in the table, no keys are active when the keyboard is locked.

Printer Status

The printer status reports if the printer is printing. Table 1-4 shows the printer status messages and symbols, and what they mean.

Mode Status

Mode status indicates the character mode that can be entered into the current field. The modes are: numeric only, any anumeric character, or insert mode only. Table 1-5 shows the connection status messages and symbols, and what they mean.

Current LU Status

The current LU status indicates the logical unit number that your PC is using while acting like a 327x terminal. A number between 2 and 33 displays.

If the system administrator assigned a specific LU number in your user profile assignment, that number displays. If not, the number is the LU that 3270/SNA attached to your PC when you first entered terminal emulation.

If you are using two display LUs at once, the LU status shows which one is in operation at the moment.

Status Messages

Status messages inform you that you have taken an action, that an error has occurred, or that the host computer has taken an action.

The errors may cause the keyboard to lock. To clear a locked keyboard, press <RESET>.

Error messages may occasionally display at the top of the screen rather than on the status line. Copy the information that displays (or press <SHIFT-PrtSc>) and contact your administrator. Having this information available will help resolve the problem.

Using the Command Menu

At the 3270/SNA emulation screen, you have access to a Command Menu that lets you do the following:

	Examine PC keys that have been defined as 3270 function keys.
	Capture print data from the mainframe into a DOS file.
	Exit from terminal emulation.

Any time you want to display the Command Menu, shown in Figure 1-3, press <F3>. If the host computer is processing data, it continues doing so, though the host data is not visible on your screen. You can return to the application from the Command Menu, which makes the application data visible again.

When you display the Command Menu, you can use only the function keys that are listed on the menu. The rest of the keyboard is locked.

If the menu on your PC looks like Figure 1-3, you can exit and release the sessions with the host, or exit and hold the sessions with the host. When you exit and release a host session, you exit terminal emulation and terminate the session. When you exit and hold a host session, you exit terminal emulation but your host session remains active. You can then resume the host session at any time.

If the menu looks like Figure 1-4, exiting automatically releases sessions with the host.

The sections that follow describe viewing keyboard definitions and exiting from emulation. For information on capturing print data into a DOS file and controlling exiting from emulation, see Chapter 2.

Viewing the Keyboard Definitions

From the Command Menu, press <F1> to examine the 3270 function keys that are defined for the PC. The Keyboard Definitions screen appears.

The Keyboard Definitions screen lists the keys in alphabetical order according to their 3270 function key name. To return to the Command Menu from the Keyboard Definitions screen, press <F10>.

When an application requires you to use a 3270 function key, such as <PF1>, use the key sequence shown in the Keyboard Definitions screen.

If you or your adminstrator have customized a special keyboard file for your use, the definitions in that file appear on the screen. For details about these files, see the section, "Customizing the PC Keyboard," in Chapter 2.

If you have a 3270/PC, you can load a special program to accommodate the keyboard on your unit. Then, some of the keys you use will differ from those shown in this section. For more information see the section, "Using the 3270/PC Keyboard," at the end of this chapter.

Many of the 3270 keys require you to use a two-key sequence on the PC. To use a two-key sequence, press and hold down the <ALT> (or <CTRL> or <SHIFT>) key, then press the function key. The Keyboard Definitions screen uses abbreviations for the <ALT> , <CTRL>, and <SHIFT> keys. The <ALT> key is represented by a-, the <CTRL> key by c-, and the <SHIFT> key by s-.

Table 1-6 lists the 3270 function keys, their key sequence on the PC, and a brief, general description of their functions. The table shows the default mappings used if no customized file or 3270/PC keyboard program is involved.

Managing multiple Sessions

You or your administrator can set up 3270/SNA so that you have multiple concurrent sessions available with the same host. You can have up to four total sessions, with a maximum of one print session. All other sessions are display sessions.

To switch from one display session to another, use the FLIP key, which is defined as <F8> by default.

Note that a keyboard definitions file can change the key that performs the Flip function. For more information about customizing keyboard definitions, see the section, "Customizing the PC Keyboard," in Chapter 2.

As you flip from one session to another, the display on your PC screen changes, along with the LU status and other messages.

For information on how to enter emulation with multiple concurrent sessions, see the section, "Entering Emulation from DOS," in Chapter 2 or talk with your administrator.

Exiting from 3270/SNA Terminal Emulation

There are three ways to exit the 3270/SNA terminal emulation option:

	Go to the Command Menu, then select an exit function. You return to the DOS prompt. See the previous section, "Using the Command Menu," for additional information.
	Press the hotkey.
	Turn off or reboot the PC, which logs you out of VINES. Wait for about two minutes before trying to return to 3270/SNA terminal emulation.

If your menu offers two exit options (Figure 1-3), you can choose how to exit 3270/SNA terminal emulation from the Command Menu.

You can release sessions with the host by pressing <F7>, or you can hold sessions by pressing <F9>.

Before you exit and release sessions, be sure you have followed the necessary procedures for logging out of your host computer. The system administrator will tell you what those procedures are. You must start a new session when you re-enter 3270/SNA terminal emulation. Then, repeat the login procedures that you normally use.

If you hold sessions, you can re-enter returning to 3270/SNA terminal emulation and resume the same session with the host, or use file transfer programs. Note that the host maintains communications with the PC and may continue sending data after you have exited. When you re-enter 3270/SNA terminal emulation, you do not have to log in to the host. You can immediately begin using the application you were using when you exited.

To hold sessions or use the hotkey, you must make one or more parts of 3270/SNA terminal emulation resident in the PC before you enter emulation. The hotkey enables you to hold sessions without using the Command Menu.

If you make portions of 3270/SNA resident, they remain in PC memory until you explicitly release them or reboot the PC. Talk to your administrator, or see the section, "Using the Resident Emulation Program," in Chapter 2 for more information.

Returning to Emulation

You can return to emulation from the Command Menu by pressing <F10>. When you return to emulation, your session continues as before. Application data returns to the screen and the keyboard unlocks. You can respond to the host computer again and can enter requests from the keyboard.

If you exit to DOS with sessions held, you can return to emulation through the VINES menus. You will be in the same session as when you left emulation.

If a hotkey is available, you can press it from DOS or from any nongraphics application and return instantly to your emulation session.

For information about more advanced features, see Chapter 2.

Using a 3270/PC

This section explains two special features available for 3270/PCs:

	Using the Host Control Adapter
	Using the 3270/PC keyboard

Using the Host Session Adapter

The 3270/PC contains a Host Session Adapter to set the display of colors and highlighting on the PC screen. You can use the GA3270 program to create a special file that provides the functions of that adapter. These functions include underlining and reverse video. Alternatively, you can accept the default of CGA.

Do not use the adapter file along with the 3270/PC Control Program; it will not work properly. For details, see the section, "Using Adapter Files," in Chapter 2.

Using the 3270/PC Keyboard

For 3270/PCs, there is a special keyboard driver program, 3270PCKB.COM. It allows you to use the special keys on the 3270/PC keyboard. Without this program, the keyboard functions as a standard DOS keyboard.

3270PCKB is memory resident, and must be loaded at the DOS prompt or from a batch file before entering emulation. When the command is executed, the PC displays a message that the keyboard translator is installed. Do not use 3270PCKB with the 3270/PC Control Program.

When you use 3270PCKB, a special set of keyboard definitions is in effect, as shown in Table 1-7.