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185
Communications Mechanism
Section 9-1
Polling Node
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.
Note 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.
9-1-2
Setting the Polling and Polled Nodes
Use the Programming Device for the PLC to set Units as polling node or
polled node in the DM parameter area.
CS-series Controller Link Units
CVM1 and CV-series Controller Link Units
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 10-7 Handling Precautions), set the Units all
nodes as polling nodes (set the polling node/polled node bit to
“
0
”
).
Check
Token circulation
cycle
Polling cycle
Communications cycle time
Check
Polling cycle
Token circulation
cycle
Communications cycle time
0
-
0 0 0 0 0 0
15 14 13 12 11 10 9
8
0 0 -
-
0 0 0 -
7
6
5
4
3
2
1
0
DM 30000 + 100
×
N
N: Unit number
-: Other settings
Polling node/polled node bit
0: Polling node
1: Polled node
0
-
0 0 0 0 0 0
15 14 13 12 11 10 9
8
0 0 -
-
0 0 0 -
7
6
5
4
3
2
1
0
DM 2000 + 100
×
N
N: Unit number
-: Other settings
Polling node/polled node bit
0: Polling node
1: Polled node
Summary of Contents for CS1W-CLK12-V1
Page 3: ...iv ...
Page 5: ...vi ...
Page 9: ...x TABLE OF CONTENTS ...
Page 11: ...xii ...
Page 59: ...42 Component Names and Functions Section 3 1 Dimensions Unit mm ...
Page 62: ...45 Component Names and Functions Section 3 1 Dimensions Unit mm ...
Page 91: ...74 CVM1 and CV series Optical Ring Controller Link Units Section 4 2 ...
Page 108: ...91 Setting Data Links Section 5 2 Device Information Setting Data Link Tables ...
Page 125: ...108 Checking Data Link Status Section 5 4 ...
Page 181: ...164 Setting Routing Tables Section 7 4 ...
Page 199: ...182 Memory Areas Related to Duplex Operation Section 8 6 ...
Page 275: ...258 Handling Precautions Section 10 7 ...
Page 298: ...281 CS series Optical Bus Controller Link Units Appendix C Dimensions Unit mm 101 35 130 ...
Page 299: ...282 CS series Optical Bus Controller Link Units Appendix C ...