Symmetricom XLi IEEE 1588

XLi IEEE 1588 Clock 71

997-01510-03, Rev. C, 12/12/2006

SSSSSSSSSSSS SSSSSSSSSS SSSSSSS S SSS S SSSSS S

Alarms - General Information

With Alarm Disabled, an F73 indicator does not trigger and alarm when it enters an Unlocked or Fault

state.

With Alarm Enabled, an F73 indicator triggers an alarm when it enters an Unlocked or Fault state, and

the following events take place:

• The Alarm Status LED changes color from green to amber or red (See “Alarm Status LED” on

page 25.)

• The ALARM output on the rear panel changes from low Z to high Z (impedance).

• If configured, SNMP sends a trap out over the network port. (See “C: SNMP” on page 151.)

The following items may delay an unlocked or fault state from triggering an alarm immediately:

• Timeout and Timeout Delay postpone Time Error alarms for a user-configured interval. See

“Timeout and Timeout Delay” on page71.

• Power-on Alarm Suppress prevents alarms from being triggered for a user-configured interval

after the XLi boots and starts. See “Power On Alarm Suppress” on page72.

Time Error and Time Threshold

Time Threshold sets the threshold in ns above which Time Error triggers an alarm. When the oscillator’s

predicted worst-case time error (“F13 – Time Error” on page52) exceeds Time Threshold, Time Error

enters a fault state.

Note: When Time Threshold is set to zero, it defaults to an appropriate value for the type of refer-

ence source. For example, when Time Threshold is set to “0”, the XLi applies 150 ns as the

value while the reference locked to a GPS reference.

LED Blink

When LED Blink is enabled, the Alarm Status LED on the front panel blinks when it is green or yellow.

The LED does not blink when it is red, even if LED Blink is enabled. Some users disable LED Blink to

ensure that the LED’s color (state) is displayed without interruption.

Timeout and Timeout Delay

Timeout and Timeout Delay allow you to add the dimension of time to the Time Error indicator. With

Timeout disabled, a Time Error fault triggers an alarm immediately. With Timeout is enabled, a Time

Error fault starts counting down the number of seconds specified by Timeout Delay. When the Timeout

Delay countdown finishes, the Time Error fault triggers an alarm. (Note: the Alarm Status LED on the

front panel turns amber while the Timeout Delay is counting down). If the Time Error fault returns to an

OK state during the Timeout Delay countdown, the countdown clears. A new Time Error fault starts the

Timeout Delay countdown from the beginning. In other words, Timeout Delay countdown does not keep

track of the cumulative duration of multiple Time Error faults.