Troubleshooting Guide

Table of contents

3270 and 5250 emulation troubleshooting checklist

  1. Did the client fail to connect?
  2. Did the Alternate Terminal interface fail to work with the emulator client?
  3. Are you having trouble connecting to the host when using file transfer on a 5250 emulator session, using the HODCached applet, or loading the Database On-Demand applet?
  4. Are the remapped Alt-key combinations not working as expected?
  5. On a Linux or AIX machine, is the Meta modifier being processed with the Alt modifier when remapping key combinations?
  6. Are the browser, Host On-Demand session, and the Linux x-window system unresponsive?
  7. Did the URL display errors under Netscape 4.x on Chinese-Traditional Windows platforms
  8. Did the F10 key fail to function in Host On-Demand with Netscape on the UNIX platform?
  9. Did transferring large UTF-8 files to a host hang the session?
  10. Are Database On-Demand and the 5250 File Transfer functions not able to connect to a V5R1 iSeries host?
  11. Did Simplified Chinese characters display incorrectly when using Red Flag Linux 3.0?
  12. Did Simplified Chinese characters display as square symbols?
  13. Are you having trouble typing in text fields?

Did the client fail to connect?

If the emulator client applet loads but the emulator session does not connect, try the following:

  1. Check for messages in the OIA area of the session window. For example, look for COMM or MACH messages on the lower left portion of the session window. To see an explanation of the COMM and MACH messages, do the following:
    1. Click Help on the Host On-Demand session menu. The Help system loads in the default system browser.
    2. Select the Index tab.
    3. Click O. Click OIA in the index to display a list of the messages.
    4. Click on the message you want to see.
  2. Make sure the parameters on the Telnet server and client match and fix them if they do not.
    1. Verify that the host specified in Host On-Demand's configuration is the same as the hostname configured for the TN3270E Server.
    2. Verify that the port number specified in Host On-Demand's configuration is the same as the port number configured for the TN3270E Server.
  3. Make sure that TCP/IP is working on both machines and that all the connections are active by pinging host names and IP address.
    1. On the Host On-Demand client workstation, at a command prompt, ping the client itself by IP address to verify that the workstation TCP/IP configuration is working. For example, if the Host On-Demand client workstation has an IP address of 255.123.123.3, type ping 255.123.123.3.
    2. On the Host On-Demand client workstation, ping the client itself by host name to verify that the workstation TCP/IP and DNS configuration is working. For example, if the Host On-Demand client workstation's hostname is myclient, type ping myclient.
    3. On the emulator host server, ping the server itself by IP address to verify that the server TCP/IP configuration is working.
    4. On the emulator host server, ping the server itself by host name to verify that the server TCP/IP and DNS configuration is working.
    5. On the Host On-Demand client workstation, ping the TN3270E Server machine by IP address to verify the TCP/IP connection is working.
    6. On the Host On-Demand client workstation, ping the TN3270E Server machine by host name to verify that the TCP/IP and DNS connection is working.
    7. On the emulator host server, ping the Host On-Demand client workstation by IP address to verify the TCP/IP connection is working from the server end.
    8. On the emulator host server, ping the Host On-Demand client workstation by host name to verify the TCP/IP and DNS connection is working.
    9. On a command line, type nslookup w.x.y.z, where w.x.y.z is the dotted decimal address of the host. If the client is given a numeric address, it contacts the local DNS to get the host name. Sometimes the DNS is not set up properly for this reverse look-up. If the DNS is not setup properly, add the host name and address to the HOSTS file on the client.
    10. Make appropriate changes to the server, the client or the Redirector based on the results you receive.
  4. Check the message log for the Telnet server defined for the Host On-Demand client session. Refer to the documentation provided with the Telnet Server software.
  5. Check the Telnet Server on the z/OS or OS/390 computer by reviewing the system console for EZZ6034I messages. EZZ6034I is always written for abnormal disconnects. You may need additional information add DEBUG DETAIL in the TCPIP.PROFILE under the "TELNETPARMS." When this debug options is enabled, EZZ6034I for all disconnects, EZZ6035I will also be writtin prior to the EZZ6034I. EZZ6035I contains more information about the reason for the connection problem.
  6. Check that the following ports are open through the network routers and firewalls from the client to the Web server, Service Manager, and Telnet server. Refer to your server operating system and router documentation for more information regarding ports.

Did the Alternate Terminal interface fail to work with the emulator client?

If you are using an old HTML file from a previous release, the Alternate Terminal interface may not come up or a Null Pointer exception message may be displayed when starting a session. If this happens, you may need to edit the HTML file, and replace any occurences of scbase.jar or scbase.cab and scfull.jar or scfull.cab with sccbase.jar or sccbase.cab.

Are you having trouble connecting to the host when using file transfer on a 5250 emulator session, using the HODCached applet, or loading the Database On-Demand applet?

If you are using file transfer on a 5250 emulator session, using the HODCached applet, or loading the Database On-Demand applet and having host connection problems, check to see if you have a classes.zip entry in your CLASSPATH. If so, remove it but be aware that other programs may require this classpath entry.

Are the remapped Alt-key combinations not working as expected?

The JVM in Internet Explorer handles key events differently according to its level. Remapped Alt-key combination key events are sometimes sent to the menu even after the action for the remapped key is taken. The result is that focus is put onto the menu and remains there. To regain focus, click on the active screen.

To avoid this, try using JVM levels 3167 and later.

On a Linux or AIX machine, is the Meta modifier being processed with the Alt modifier when remapping key combinations?

On AIX and Linux, depending on the keyboard assignments for the machine and the level of Java installed on the machine, the Meta modifier might be processed with the Alt key. Thus, if you press the Alt key on these systems, you receive Meta-Alt key events. This causes problems if your Host On-Demand session is defined on Windows, a key remap assignment is done using the Alt key, and you start the session on a Linux or AIX client.

For example, the administrator defines a session using the Deployment Wizard on Windows. In this session, the administrator maps the Reset key function to the Alt-R key combination. If a user starts the Host On-Demand client on a Linux or AIX machine that processes Meta-Alt for the Alt key, they will not be able to process the Reset key function correctly. Every time that they enter the Alt-R key combination, Host On-Demand receives a Meta-Alt-R key event, which will not process the Reset function.

To fix this, the administrator of the AIX or Linux machine must use the xmodmap command to change the keyboard assignments so that Alt is processed without the Meta modifier. Note that the xmodmap command affects the current X window session, so logging out restores the key assignments to their original values.

A specific example for AIX follows:

The 1.1.5 JDK shipped under Netscape processes Meta-Alt for the left Alt key if the keysym for the right Alt Key is not assigned to mod1.

When using a non en_US.8859-1 keyboard, the Xserver may have the right Alt key, Alt_R, mapped to Mode_switch (or a key besides Alt_R). Additionally, mod1 may have the left Alt key, Alt_L, solely assigned. When mod1 only has Alt_L assigned, and this key is pressed, Meta+Alt is generated. To avoid the Meta modifier from being added to the key event, the Alt_R key must be added to mod1. To accomplish this, do the following (written in pseudocode):

xmodmap
if ((mod1 = Alt_L) and (mod2 = Mode_switch, Mode_switch))
xmodmap -pke
if (keycode 70 = Mode_switch)
xmodmap -e "add mod1=Mode_switch"
Are the browser, Host On-Demand session, and the Linux X-window system unresponsive?

This problem occurs under Red Hat Linux and Netscape 6 (or later) with the IBM Java runtime environment (JRE) or the IBM JDK for Linux, Service Release 8 and below. When an empty pull-down menu or choice list is clicked (that is, when the leftmost object on the Macro Manager Toolbar has no macros present to choose from), the browser, Host On-Demand session, and the Linux X-windowing system become unresponsive.

You can avoid this problem by not clicking the empty pull-down menu, or clicking the pull-down menu only when there is at least one item to select. However, if the Linux X-window system becomes unresponsive after clicking the empty pull-down menu, restarting the X-window system returns control back to normal (without having to reboot the entire machine).

Try upgrading to the IBM Linux JDK, Service Release 9 or above. You can download this from IBM DeveloperWorks at http://www-106.ibm.com/developerworks/java/jdk/index.html. New users need to register before downloading it.

Did the URL display errors under Netscape 4.x on Chinese-Traditional Windows platforms?

If you are using Netscape 4.x on a Chinese-Traditional (Taiwan) Windows platform, URLs that are displayed on 3270 and 5250 session screens may be truncated and overlap with text on the same row. Try upgrading to Netcape Version 6 or later.

Did the F10 key fail to function in Host On-Demand with Netscape on the UNIX platform?

The Unix version of Netscape is built on the Motif toolkit, which binds the F10 key to a command that activates the menu bar by default. As a result, the terminal emulation screen of Host On-Demand running on Unix versions of Netscape cannot handle the F10 keystroke.

There are two workarounds:

Did transferring large UTF-8 files to a host hang the session?

While using Netscape 4.x, transferring large UNICODE UTF-8 files to a host may cause the emulation session to hang. Try upgrading to Netscape Version 6 or later.

Are Database On-Demand and the 5250 File Transfer functions not able to connect to a V5R1 iSeries host?

If the Database On-Demand and the 5250 File Transfer functions of Host On-Demand are not able to connect to a V5R1 iSeries host that has long password support enabled in a Netscape 4.x browser, try upgrading your browser.

Did Simplified Chinese characters display incorrectly when using Red Flag Linux 3.0?

If Simplified Chinese characters do not display correctly, your Java plug-in may not support the correct font properties file (font.properties.zh). Try installing a different Java 2 plug-in.

Did Simplified Chinese characters display as square symbols?

On the Windows 2000 Simplified Chinese platform, double-byte characters are displayed as square symbols in Netscape 6 and Internet Explorer 6. To display these characters correctly, try installing the Sun 1.4 Java plug-in or the IBM 1.3.1 Java plug-in.

Are you having trouble typing in text fields?

When using Host On-Demand with Java 1.4.0, you may lose focus when making a selection in a choice box, and you will not be able to type in text fields. To regain focus, you may either click off of Host On-Demand into another application, your desktop, or another location, and click back, or you can minimize and then maximize the Host On-Demand panel. Try using Java Version 1.4.1.

Top of page Table of contents