a. Any enabled and valid input reference becomes available again: If one or
more references return and are declared valid before the Holdover period
has expired (even momentarily, i.e. for at least one second), VersaSync
exits the Holdover mode and returns to its fully synchronized state.
b. The Holdover Timeout period expires. In this case, VersaSync will declare
loss of synchronization.
Note that Holdover mode does not persist through reboots or power cycles. If a
reboot or power cycle occurs while VersaSync is in Holdover mode, it will power-
up and remain in a “not synchronized” state until at least one valid Time and 1PPS
input reference becomes available again. While in this state, NTP will be
Stratum15 and outputs will not be usable. If the input references are restored and
then lost or declared not valid again, VersaSync will then go back into Holdover
mode.
What is "Holdover Timeout"?
Holdover Timeout is the user-configurable allowable time period in which Ver-
saSync remains in Holdover mode before it declares loss of synchronization. Hol-
dover Timeout can be adjusted according to application-specific requirements
and preferences. See below for recommendations on how long (short) the Hol-
dover Timeout should be.
How to configure Holdover Timeout
To set the Holdover Timeout value:
Navigate to MANAGEMENT > OTHER: Disciplining, and click the GEAR icon
in the Status panel:
For more information on the TFOM value and Phase Error Limit, see "Con-
figuring the Oscillator" on page223.
220
CHAPTER 3 • VersaSync User Manual Rev. 12
3.3 Managing References
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