Symmetricom XLi IEEE 1588 manual F74 Clock Source Control

SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

The XLi responds:

F73 POWER-ON MINOR ALARM SUPPRESS 300

To set a new Power-On Alarm Suppress value, enter the following string, replacing <SEC> with the number of seconds (Range 0 to 86,400 seconds), enter:

F73 SUPPRESS <SEC>

The XLi responds:

OK<CR><LF>

F74 – Clock Source Control

Use function F74 to select the primary and secondary reference sources and configure the fail-over sequences. The switching modes are:

•PRI or “Primary”: Ensures the unit remains connected to the primary source and doesn’t attempt to switch. PRI is the factory setting.

•SEC or “Secondary”: Ensures the unit remains connected to the secondary source and doesn’t attempt to switch.

•PRI – SEC – SEC or “Primary – Secondary – Secondary”: the clock synchronizes with the primary source. If the primary source becomes unavailable, it switches to the secondary source and stays there, even if the primary source becomes available again. It stays on secondary even if the secondary source becomes unavailable.

•PRI – SEC – PRI or “Primary – Secondary – Primary”: the clock synchronizes with the primary source. If the primary source becomes unavailable, it switches to the secondary source. When the primary source becomes available again, it switches back to the primary.

•PRI – NSEC – PRI or “Primary – No Secondary – Primary”: the clock synchronizes with the primary source. If the primary source becomes unavailable, it switches to the secondary source. If the secondary source becomes unavailable, AND the primary is available, switches back to the primary.

Clock source switching is affected by the setting in F73 Timeout. When a reference source becomes unavailable, or unlocked, the number of seconds set in F73 Timeout must elapse before the switch occurs. While the reference source is unavailable the clock relies on a frequency source, such as its own oscillator or Aux Ref, to keep time. (If Aux Ref is available and enabled, the XLi will use Aux Ref as its frequency source. See “F113 – J3 Input Configuration (Aux Ref)” on page 104 for more information.) After the timeout has elapsed, the switching sequence begins.

When a time reference becomes unavailable, the XLi switches to the other time reference, if available. The configuration of the time reference (e.g., Primary or Secondary) and the settings in F74 – Clock Source Control (page 77) determine if and how switching takes place. If no other time reference is available, the XLi will use an Aux Ref frequency input on J3 (“F113 – J3 Input Configuration (Aux Ref)”, page 104) as its reference. If references are available, the XLi “freewheels” on its internal oscillator.

XLi IEEE 1588 Clock 77

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