System Startup, Configuration, and Shutdown Reference Manual (32650-90892)

Appendix A 193
Using the Access Port (AP)
Configuring the Console
Halting Scrolling
Entering
CTRL S causes the AP to stop passing characters from its port queues to the
consoles. The queues continue to accept characters from the system. The XOFF is not
passed to the system port being used for the transfer.
Allowing Scrolling
Entering
CTRL Q causes the AP to resume passing characters from its port queues to the
consoles if this was previously stopped by XOFF character. The XON is not passed to the
system port being used for the transfer.
Entering Escape Characters
The escape character
CTRL V nullifies whatever character follows it, except for XON and
XOFF characters. Any character following a
CTRL V has no effect on AP operation.
Changing Master Consoles
Only one console can operate as the system console at a time. It is referred to as the
master. The other, usually the remote terminal, can view data but cannot enter data until
it takes control.
Break is used to take control back and forth between the system console
and an enabled remote console. When the remote console enters
Break, it becomes the
master console, and vice versa. In order to enter data at the remote terminal, you must
press
Break.
Interpreting AP Error and Informational Messages
The AP provides two classes of messages. A message that is followed by (APERR XX) is an
error message. “XX” indicates the error number. A message that is followed by (APMSG XX)
is an informational message, although it can indicate a potential error. Error and
informational numbers may be duplicated; for example, there is both an APERR 01 and an
APMSG 01.
Error Codes and Error Messages
MESSAGE: Unable to verify assertion of RESET SYS backplane signal (APERR 01)
CAUSE: This message, displayed during execution of the RS command, means that the
backplane signal RESET_SYS- is not asserted when the AP attempts to reset the SPU.
This error might be caused by any one or a combination of four conditions.
Failure of the AP drive circuitry causes this error to be detected, and the SPU is not reset.
The circuitry that permits the AP to read this line may have failed. If this is the case, the
error message is displayed, but the SPU is reset in the proper manner.
The CIO backplane may contain a short between the RESET_SYS- line and another low
impedance line that is driving a high-logic level.
Some other device connected to the RESET_SYS- line may be driving a high-logic level that
the AP cannot overdrive.
MESSAGE: RESET_SYS backplane signal asserted, but unable to verify SPU
deassertion of PPON backplane signal (APERR 02)