Symmetricom SSU-2000e User Manual page 155

Chapter 6 Clock Module Reference Data
Communications Module
When the Communications module is installed, it performs an initial software
verification test to verify operation. If the module is installed in the SSU-2000e with
power already applied and with other modules installed, the Communications
module reads the configuration of the modules in the SSU-2000e and the modules
in all installed SDU-2000e expansion shelves. This information is saved in
nonvolatile memory on the Communications module. If power is applied to the
SSU-2000e after the Communications module is installed, it initializes before any
other module and provides configuration information to the individual modules.
The master controller function for the SSU-2000e can reside in the Communications
module or in either of the Clock modules. The priority of the selection of the module
that will provide the master controller function rests with the Communications
module, Clock A, and Clock B, in that order. In the event of removal of the module
designated as the master controller, that function automatically and seamlessly
switches to the next module in priority order.
All man/machine communications are controlled by the Communications module.
This module then communicates with the other modules in the SSU-2000e to read
configuration data, set operational parameters, and determine what type of modules
are installed. When a module is replaced, the controller loads the correct
operational parameters into the replacement module.
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