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Using a Quantum 984 HSBY System
90
840 USE 106 00 January 2003
Keyswitch Override and Run Mode
Keyswitch and
Run
You may choose to override the keyswitch on the front panel of the CHS 110
modules for security or convenience. If you override the keyswitch, the command
register becomes the means for taking the CHS 110 modules on or offline.
By default, the keyswitch override is disabled. The Hot Standby dialog allows you to
enable it.
Keyswitch
Override
If you enable the keyswitch override, the Offline/Running operating mode of the
controllers at startup is determined by the values you set to bits 14 and 15 of the
command register. These bits are represented as the Run Mode for controller A and
B (depends on designation slide switch). Remember, that when the keyswitch
override is enabled you can not initiate a program update (program xfer) at the CHS
110 module in the Standby rack.
As long as the keyswitch override is disabled, the settings for the Run Mode can be
ignored.
If both bits are set to 0, a switchover occurs and the former Primary CPU goes
offline. The new Primary CPU continues to operate.
CAUTION
Keyswitch Override Hazard
If you use the Zoom screen or RDE to enable the keyswitch override
while the Hot Standby system is running, the Primary controller
immediately reads bits 14 and 15 to determine its own state and the
state of the Standby.
Failure to follow this precaution can result in injury or equipment
damage.