Setting The Polling And Polled Nodes - Omron SYSMAC CS1W-CLK13 Operation Manual

Communications Mechanism
Polling Node
Note
9-1-2

Setting the Polling and Polled Nodes

CS-series Controller Link Units
CVM1 and CV-series Controller Link Units
Token circulation
cycle
Communications cycle time
Each Controller Link Network always has a Unit that controls communications
within the network. This Unit is called the "polling node." Normally, the node
that has the smallest node address in the network is the polling node (see
note). All Units at nodes other than the polling node are called "polled nodes"
(or polled units). The polling node controls the token, checks the network, and
performs other relevant tasks. Should the polling node break down, the node
with the next smallest node address is automatically selected as the polling
node to prevent the entire network from shutting down.
The node with the smallest node address is not always the polling node,
depending on the Unit start-up sequence, models, settings, and Unit status.
With an Optical Bus Controller Link Unit or Board, when the polling node
breaks down the next polling node is temporarily disconnected from the net-
work, reconstructs the network, and then reconnects to the network. Polled
nodes remain connected to the network.
With an Optical Ring Controller Link Unit, when the polling node is shifted, the
new polling node is not disconnected from the network.
When Controller Link Units are used in duplex operation, if there is an active/
standby switchover resulting from an error in a Unit, because the node will
temporarily leave the network before joining it again, the polling node will be
shifted.
Use the Programming Device for the PLC to set Units as polling node or
polled node in the DM parameter area.
15 14 13 12 11 10 9 8
DM 30000 + 100×N 0 - 0 0 0 0 0 0
N: Unit number
15 14 13 12 11 10 9 8
DM 2000 + 100×N 0 - 0 0 0 0 0 0
N: Unit number
Polling node/polled node bit
0: Polling node
1: Polled node
If the node is always to be connected as a polled node when the power is
turned on, set it as a polled node. If the node can become a polling node
when the power is turned on, set it as a polling node. One of the nodes set as
a polling node will serve as the actual polling node. Except for maintenance
after Unit replacement (see 10-8 Handling Precautions), set the Units all
nodes as polling nodes (set the polling node/polled node bit to "0").
Check
Polling cycle Token circulation
cycle
Communications cycle time
7 6 5 4 3 2 1 0
0 0 - -
Polling node/polled node bit
0: Polling node
1: Polled node
7 6 5 4 3 2 1 0
0 0 - -
Section 9-1
Check
Polling cycle
0 0 0 -
-: Other settings
0 0 0 - -: Other settings
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