Solving load problems

If a hardware error occurs while loading a programmed symbols buffer, IMS performs series of predefined actions.

If a hardware error occurs while loading a programmed symbols buffer:

The message used to load the programmed symbols is returned to the IMS message queue.
The terminal is taken out of service.
Exception: SLU 2 devices are not taken out of service.
The error is logged on the IMS log.
Message DFS2078 is sent to the IMS master terminal. For AOI purposes, provide the message number, if possible.

After the hardware error is corrected and the terminal is in service, the message to load the programmed symbols is resent.

If the loading of the programmed symbols fails because of an error in the message to load the programmed symbols, the operator must:

Dequeue the message. The master terminal operator might need to issue the dequeue (/DEQ) command.
Correct the error.
Reenter the transaction to resend the programmed symbols load message.

If a method is available for informing the next user of the programmed symbols buffer status, the terminals with loaded PS buffers should not be powered off. When a power failure occurs or a terminal is powered off, the contents of the PS buffers might be lost.

When a terminal is powered on, if no IMS messages are waiting to be sent to the display, an IMS response mode transaction should be entered to load all required PS buffers or some non-IMS method should be used to load the PS buffers. However, if IMS messages are waiting to be sent, and these messages require the use of one or more PS buffers, sending the queued messages must be delayed until the PS buffers can be reloaded.

For SLU 2 devices, if the PS buffers are not loaded and a message requiring the use of a programmed symbols buffer is sent to the terminal, the message is rejected and IMS:

Returns the invalid message to the IMS queue
Logs the error on the IMS log
Sends message DFS2078 to the IMS master terminal and to the node, indicating an output failure.

The terminal is left in protected mode after receipt of message DFS2078.

A user application program can be designed to queue to an LTERM an unsolicited message requiring a particular programmed symbols buffer to be loaded. The first part of the message can include a load programmed symbols data stream; however, this message cannot be processed by Message Format Service (MFS).