Long Name: Interface:Ethernet:Time Sync:Port:Synced?
Class: XNET Session
For the Protocol of IEEE Std 802.1AS-2011, this property is True when AS
Capable is True and the following conditions apply:
- If Port
State is Slave, XNET clock adjustment algorithm (servo) is in its
final stage (calibrated). Sufficient messages have been exchanged such that
synchronization quality (e.g., Offset From Master) is unlikely to improve
significantly, but no fixed metric is applied as a threshold.
- If Port State is Master and best master clock algorithm (BMCA) is
enabled, at least two announce intervals have elapsed. Master state means
that the XNET port is acting as grandmaster (the source of time in the
network), so Synced? would normally be true
immediately. When using the BMCA, the XNET port initializes assuming that it
is a potential grandmaster (Master), but when it receives an announce
message from a better grandmaster, the Port State changes to Slave. By
waiting up to two announce intervals, the XNET port avoids reporting a
false-positive from Synced? (i.e., true because it
was Master upon initialization, then false when a better grandmaster is
detected, and then true again after slave calibration).
- If Port State is Master and BMCA is disabled,
Synced? is true immediately. As BMCA is disabled,
this XNET port will act as the Master (grandmaster) indefinitely.
In the IEEE 1588-2008 standard (on which IEEE Std 802.1AS-2011 is based), this
Synced? flag is analogous to transition out of the
UNCALIBRATED state. For 802.1AS, behavior similar to this property is specified
as the AVB_Sync state of the Avnu Automotive Ethernet AVB Functional and
Where This Property Is Available:
Desktop OS: Windows
FPGA: Not supported
Web Server: Not supported in VIs that run in a web application