Sierra Video VS User Manual download pdf (Page 29)

THEORY OF OPERATION

protocol displays a message to the user that a standby processor is now available, and asks him

to press the “Control/C key combination”. After Control/C is pressed, the router configuration

screen is displayed. This serves to synchronize both processors to the same terminal screen.

Processor Health Monitoring and LEDS

Each processor monitors its own health, as well as that of the other processor, and displays a

healthy/sick indication on the processor edge LEDS. Two LEDS indicate the health of the

processor on which the LEDS are located, and two indicate the health of the other processor.

LEDc and LEDd indicate the health of the processor on which those

LEDS are located. Both processors continually monitor the following expected conditions within

themselves:

Presence of vertical sync interrupt.

Regular operation of the crosspoint control software.

Regular polling of control panels.

If any of the above cease to occur, or if a processor fails one of its startup diagnostics, it

considers itself “sick”, and it flashes its LEDd to tell the user that it has a problem. Otherwise, is

turns on LEDc to indicate that it thinks everything is okay with itself. Any time a processor is

flashing LEDd, it indicates the processor has something wrong with it. Use the terminal protocol

“D” (DIAG) screen to make sure the processor didn’t fail its startup diagnostics.

It is possible for a processor to flash LEDd briefly and then stop, if it should detect absence of any

of the above-listed activity. If this happened, it would indicate a software failure. LEDe and LEDf

indicate the health of the opposite processor. Besides monitoring their own health, both

processors continually report to and monitor the other processor. If the other processor stops

reporting that it is okay, LEDf is flashed to tell the user that the other processor is not working

properly. Otherwise, LEDe is turned on to indicate that the other processor appears to be working

properly.

Takeover by Standby Processor

As noted above, both processors monitor the health of the other processor. If the standby

processor detects that the master processor is sick, or if it detects that the other processor is not

acting as master for some reason, the standby processor will attempt to take over control of the

system as the new master processor.

Furthermore, if the master processor has determined that it is “sick” (see description of LEDd

above) or if any of the following behavior occurs in the master processor, it will shut itself down

and allow the standby processor to take over:

Unexpected processor interrupts;

Processor data bus errors.

Software integrity check failures.

Manual takeover initiation by the user via a host protocol command or terminal port “T” screen

command.

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Sierra Video VS User Manual Page 29