Rockwell Automation Allen-Bradley SynchLink 1756-DM Series Design Manual page 15

Because SynchLink is a broadcasting mechanism, the master is always
placed at the beginning of SynchLink systems, such as the star
configuration in Figure 1.1.
Figure 1.1
Star Topology
Time Master
S.L.N.C. S.L.N.C.
SynchLink SynchLink
Time Slave Time Slave
S.L.N.C. = SynchLink Node Clock
SynchLink System Synchronization
When a SynchLink system is initialized, the individual SynchLink
nodes power-up at separate times, and the individual SynchLink node
clocks begin to count at arbitrary points in time; the system is not yet
synchronized.
As the time master node clock counts, it reaches a point where it rolls
over and goes back to zero. When the rollover occurs, the SynchLink
time master transmits a beacon signal to the SynchLink time slaves;
the beacon is included in the control field of the transmitted message.
When the SynchLink time slave receives the first message with the
beacon signal, it begins to adjust the 1 m S time base of its node clock
to synchronize with the time master node clock.
SynchLink
S.L.N.C.
Hub
S.L.N.C. S.L.N.C.
SynchLink SynchLink
Time Slave Time Slave
Publication 1756-TD008A-EN-P - August 2002
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