52 | EdgeSync Manual rev 1 orolia.com
The maximum time the clock stays in holdover state is defined by a holdover interval. By default, this
value is set to 1000 seconds which gives about 1 microsecond error at the end of holdover interval.
After holdover interval expires, the clock switches to the FREE RUNNING state, and its accuracy is reset
to UNKNOWN (0xFE).
UNKNOWN/ERROR State
The EdgeSync clock has entered a failed or error condition and the sync state is unknown.
Unicast Operations
By default, unicast operations are disabled and the EdgeSync port operates in multicast mode. After
unicast mode is enabled no multicast communications are possible.
The PTP port can be switched to unicast operations and back at any time using the
PTP :: Port and PTP
:: Unicast Sections of this User Guide.
Unicast Master
A EdgeSync port in unicast master state can support:
• Slave nodes which dynamically request unicast message transmission services from the master
using the unicast negotiation mechanism.
• Slave nodes which do not support the unicast negotiation and simply rely on the reception of
unicast messages from the master.
To accept unicast negotiation requests from slave nodes the master needs to be configured as follows:
• Unicast negotiation must be enabled.
• Slave acceptance filter must be populated. Note that in the current design, the slave
acceptance filter is not user-configurable, and it is set to accept all slaves.
To provide message transmission services to slave nodes which do not support the unicast negotiation
the master needs to be manually configured with the list of static slave nodes.
Enabling Master Unicast Negotiation
The unicast negotiation state is controlled by the PTP :: Unicast Section of this User Guide.
When unicast negotiation is enabled the master accepts unicast transmission requests from
negotiation-capable nodes. If a node is allowed by the acceptance filter and if enough resources are
available, the master grants message transmission services to that node.
If unicast negotiation is disabled no new requests are accepted, but all existing grants remain serviced
until they are either expired or cancelled.
Maintaining Master’s Slave Acceptance Filter
Note: In the current implementation, the slave acceptance filter is not user-configurable and it is
set to accept all slaves. In that respect, the following documentation on slave acceptance filter is only
for academic purpose.
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General