Hardware : Terminals

Using a terminal on the system is very straight forward and should need no further comment. This chapter deals with connecting a terminal to the system and trouble-shooting it in case of problems.

Configuring the terminal for Unix

Full details of this are contained in the instructions for installing the Unix operating system. To summarise:

• Connect the terminal to a free port.
• Check /etc/inittab is set to the correct speed.
• Check /etc/ttytype is set to the correct emulation.
• Enable the port.

Terminals should be set up as follows:

baud 38400, no parity, 8 data bits, 1 stop bit.

The emulation should tally with the choice made in the device file we would recommend that a Wyse 60 emulation should be used. Check that the country setting corresponds with the keyboard you have, normally 'UK'. (This doesn't mean the pound sign will automatically work, the best way to deal with this is to use the hash sign and get the printer to turn this into a pound sign).

The exact details of what parameters are available and how to change them are contained in your terminal manual - please refer to this. Some parameters are a matter of individual choice.

Terminal setting within the Vet software

Within the Premvet 5 software there is an entry for each tty line that can be used for a terminal. This is accessed with the 'Set device' option within the parameter set up menu. 29. As far as terminals are concerned the only relevant bit is the emulation. The emulation in the device entry MUST agree with the terminal type.

If the emulation you are planning to use is unknown to the VET system there is an option again in parameter set up called terminal database. This option is used to enter the appropriate codes for the terminal. We would not expect you to change this option and details for doing so will not be given here.

Note: If you have a line set for dial-up access then setting the terminal type to -1 will allow different terminals to be used. Note: Edit the file 'device' manually with vi and not via a menu option). This will force the Vet system to look at the Unix set up to determine terminal type and settings and will give you the basic terminal capabilities.

Troubleshooting if a terminal does not respond

This outlines the procedures to be carried out in the event of apparent malfunction of a terminal.

The procedures are simple and systematic and can and should be followed by any operator prior to seeking further guidance from or reporting a fault to your hardware maintenance company.

• The first stage is to wait. As the system becomes more heavily used, 'response time' increases. During periods of peak activity, the terminal may accept keystrokes without 'obeying' them, giving the impression of being locked completely. Wait a minimum of 60 seconds.

• Ctrl-S may have inadvertently been pressed. This has the effect of pausing scrolling in some software. Press Ctrl-Q to continue.

• If the terminal responds to input, but does not display the typed characters on the screen, (a non-echoing terminal) do the following:
  1. Press Ctrl-J
  2. Type:

     stty sane

     and press Ctrl-J. The terminal does not echo what you type, so enter it correctly. Then press Ctrl-J. Everything should be o.k. now. If not, try pressing Ctrl-D and log in again, or do a complete shutdown.

• Next check for connectors not being properly attached. At the same time check and see whether the console has received messages similar to 'getty cannot open' or 'getty keeps dying'. This means that there is a hardware problem on the board supporting this terminal. Disable the tty concerned to prevent the continual messages disrupting work on the console, and call out the hardware maintenance company. (Remember to re-enable the tty again to check if working!)

  Disable the terminals with the command:

  disable ttyXXX

  where XXX is the full device name e.g. tty002

• Something may have set the terminal's internal software to an unusual state, e.g. by unexpected control characters or by someone tinkering with the terminal set up parameters. Often this can be corrected by switching the terminal off and on again. This will always result in a blank screen, but you will still be at the same stage in the program you were running, so issue whatever sequence of commands will get you running again with a refreshed screen display, by going back to the main menu, etc.

• Next try resetting the hung terminal from one that is still functioning, as it may be hung by a runaway process. You will need to know the device name that corresponds to the problem terminal. Find this out either by looking at the label on the connector, if present, or look at the device file to see which device corresponds with which terminal number as far as the veterinary software is concerned. The terminal number and device can be displayed by entering a question mark at the main menu prompt.

  Log on as root and type the command:

  ps -t ttyXXX

  where for ttyXXX you substitute the name of the device the problem terminal is attached to.

  You will see a display similar to:

    PID     TTY        TIME CMD
    962   tty02    00:00:00 login
   2129   tty02    00:00:01 sh
  27168   tty02    00:00:00 sh
  27192   tty02    00:00:00 run14
  

  Choose the line with run14 in the CMD column, and note this number.

  Type the following command:

  kill XXX

  Where XXX is the PID number you found in the earliest line.

  The login prompt should now appear on the problem terminal.

  If it does not, the problem is either the terminal set up has gone, so check that, or there is a hardware problem or the cabling is interrupted. If you have more than one terminal, try swapping the problem one with one that is known to be working. If the working one fails when attached in the position of the suspect one, then the problem is cabling. If the suspect one does not work when attached in the place of the working one, then the terminal is broken. Either way consult your hardware maintenance company.

Troubleshooting if the console does not respond

Try pressing the 'Caps-Lock' or 'Num-Lock' keys and see if the indicator lights corresponding to these keys go on and off. If they do, try resetting the terminal as explained in the 'Terminal does not respond' section.

If the lights don't go on and off, unplug and reconnect the keyboard and see if the problem goes away. If the problem occurs repeatedly or this does not fix the problem, there is a hardware problem with the keyboard.