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Master Node
SynchLink
Daisy Chain Topology
In the daisy chain topology, the SynchLink system starts at the master
node and ends at an end node but may also include center nodes that
receive and transmit data; the only difference between center and end
nodes is their physical location. You can use a maximum of 10
nodes, including the master node, with this topology.
Figure 2.2
Center Node
In this topology, time synchronization occurs according to the
following rules.
· Each node, except for the master node, enables its transmitter
immediately after it has received the first message from the
upstream node.
· Each node can generate and transmit the beacon signal
regardless of whether it has received one or not.
· Each node is a time slave of its upstream node and will attempt
to synchronize with it.
The master node must be set as the SynchLink Time Master. Its node
clock is the SynchLink system clock. After power-up, the Master node
begins to transmit a beacon message every 50 m S. As soon as the
downstream node receives the first beacon message, it starts to
synchronize its node clock with the master node clock and begins to
send messages to its downstream node. Eventually, this process
propagates down the daisy chain until all nodes are synchronized
with the master.
The advantages to using the daisy chain topology are:
· The topology does not require a hub and is easier to install.
· Data moving downstream can be modified from node to node.
The disadvantage to using the daisy chain topology are:
· A single node failure brings down the link, unless bypass blocks
are used. For more information on bypass blocks, see page 3-8.
· It is more difficult to troubleshoot.
· Axis and buffered data cannot be passed through without
intervention from the local host controller, requiring additional
time.
For more information on the configurations available in the daisy
chain topology, see page 4-9.
Center Node
Publication 1756-TD008A-EN-P - August 2002
2-3
End Node
43119
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