Module Descriptions
GARD 8000 SYS RFL Electronics
April 23, 2015 6-8 973.334.3100
Each GARD Controller contains a monitoring system, which monitors vital hardware signals within
the module. The PowerPC CPU and DSP Processor monitor their own operations and interfaces.
A dedicated communications channel (“mirroring”) is used to transfer system information, such as
configuration, from the currently active to the inactive module. This allows a newly installed (and
inactive) controller to become configured and ready to take over control if required.
Dedicated signaling channels on the midplane are used to convey faults and activity states of the
Controllers to their companion modules.
The active module has full control of the system, just as if it was the only one present. The inactive
module is idling in full operational condition. All drivers of its signals to the backplane, Ethernet, etc.
are disabled.
Besides the Controller, no “slave” module (channel module or functional module) in the GARD
chassis is aware of the presence of two Controllers, nor does it know which one is active. The system
operates the same way, regardless of which Controller is active.
If an out-of-bounds condition is detected within a Controller, an on-board fault condition is set. Based
on the rules of redundant operation, the active and inactive states may be swapped between the two
Controllers.
The redundant swap is a very severe event and may momentarily affect data traffic. It occurs after a
certain delay from the onset of a fault, to prevent “flip-flopping” between the modules as the system
may experience a disturbance following a swap. It is intended to ensure continued system operation
despite a failure of the controller.
6.1.2.4 CONTROLS AND INDICATORS
LED Indicator
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