Operating In Failure Mode; Fault Mode Responses And Actions - Symmetricom TSG-3800 Series User Manual

Table 3-4. Fault Mode Responses and Actions
Fail the Input and
Mode
Switch References
FAIL YES
Input reference is automatically rejected. The TSG-3800 switches to another input or into Holdover.
Causes a minor alarm when exceeding the operator-set threshold if another valid reference is available.
If no valid reference is available, the TSG-3800 causes a major alarm and places the clock(s) into
Holdover. A failed input is automatically reported over the EIA-232 port. In a ST2E/ST3E TSG-3800
configuration, if the Stratum 2E clock enters Holdover, the ST3E clock is also placed in Holdover Mode.
ALARM NO
Causes a minor alarm when exceeding operator-set threshold and is reported over the EIA-232
port. Input reference or module is not automatically rejected.
REPORT NO
Reports the event to the EIA-232 ports, without alarming, when exceeding operator-set threshold.
IGNORE NO
Disables switching and alarming. Does not report to the EIA-232 ports.

Operating in Failure Mode

In the event of a module failure, the TSG-3800 provides continuous operation
through multiple levels of redundancy and multiple switching.
Input Module Failure
If an Input module fails, an alternate input is selected if available. If an alternate
input is not available, the CPU module places the unit in the Holdover mode of
operation until a reference input has been restored to service. Entry and exit from
Holdover mode is done through processor control of the Clock modules such that
no significant phase steps or frequency changes occur.
CPU Module Failure
If the CPU module fails or is removed for service, the Clock modules automatically
switch to Holdover Mode, as described in
Clock Module or Frame Generator Failure
The TSG-3800 uses Clock modules and Frame Generator modules in pairs: Clock
A works with Frame Generator A and Clock B works with Frame Generator B. If the
selected Clock Module or Frame Generator module fails, the alternate Clock/Frame
Generator module pair is selected for use by the Output modules.
Output Module Failure
If there is a failure in any of the Output modules, the redundant module continues to
provide outputs on a one-for-one basis if redundant output strategy is configures for
the TSG-3800.
12778474-002-2 Revision F – March 2004
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Set Alarm Relay and
Illuminate Indicators
YES
YES
NO
NO
Holdover
Operating the TSG-3800
Viewing Alarm Conditions
Report on EIA-232 Ports
YES
YES
YES
NO
Mode, on page 97.
TSG-3800 User's Guide 95