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Last Modified: February 7, 2020

Enables (runs) the Best Master Clock Algorithm (BMCA) of the time synchronization Protocol.

The BMCA dynamically exchanges messages over the network to select the best grandmaster in the network, and to change all port states in order to transfer timing messages from the selected grandmaster to slaves.

Data type: datatype_icon

Long Name: Interface:Ethernet:Time Sync:BMCA Enabled?

Class: XNET Session

Permissions: Read/Write

When this property is True, Protocol runs the BMCA. The Port State property is determined from operation of the BMCA. The XNET interface is capable of acting as a grandmaster. Therefore, the BMCA can set the Port State property to Slave (i.e., XNET interface receives time) or Master (XNET interface sends time). The Port State Configured property is not used while the BMCA is enabled. The BMCA uses the following properties in order for its selection of grandmaster (with exceptions for topology):

  • Priority1
  • Clock Class
  • Clock Accuracy
  • Clock Offset Scaled Log Variance
  • Priority2
  • Clock ID

When this property is False, the BMCA is not operational. The False value is useful for in-vehicle applications in which the topology for time synchronization is considered to be part of the vehicle's static design. The Port State Configured property must be written in order to specify the Master or Slave state for the port. The read-only Port State property reflects Port State Configured. When an XNET session is started on a port that is set to Tap mode, this property becomes read only and its value cannot be modified.

Where This Property Is Available:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application

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