Network Parameters; Specifying Network Parameters - Omron SYSMAC CS1W-CLK13 Operation Manual

Communications Mechanism
9-1-3

Network Parameters

Maximum Node Address
No. of Polled Nodes Per
Communications Cycle
No. of Event-frames per
Communications Cycle
9-1-4

Specifying Network Parameters

Note
220
Network parameters are also used to control network operations. Network
parameters are read from the polling node and distributed to all other nodes
when the Controller Link Network is started. In this way, all nodes on the net-
work always have the same network parameter settings. If nodes are con-
nected to the network halfway during network operation, the network
parameter settings will also be distributed to these nodes when they are con-
nected. The following three network parameters can be specified.
This parameter specifies the maximum node address of nodes to be checked
by the polling node. The default is 62 (or 32 for Optical Bus Networks). Reduc-
ing the setting of this parameter reduces the number of nodes checked by the
polling node and can thus avoids unnecessary check operations. However, if
the network contains nodes with node addresses greater than the setting of
the parameter, these nodes will not be connected to the network.
This parameter specifies the number of nodes to be checked (polled) by the
polling node during each polling cycle. The default is 4. Setting this parameter
to a high value increases the communications cycle time, but reduces the time
required to recognize that nodes have been removed from or added to the
network. Reducing the setting of this parameter shortens the communications
cycle time but delays a network response when a node is disconnected from
or connected to the network.
This parameter specifies the maximum number of event frames (communica-
tions other than data links, such as message service transmissions) that can
be transferred during a communications cycle. Specify a value in units of 128
bytes. The default is 35 (128 × 35 = 4,480 bytes).
Increasing the setting of this parameter increases the communications cycle
time but allows for more event communications such as the message service.
Too small a parameter value restricts event communications, resulting in an
error. See 9-2 Communications Cycle Time (on page 221) for the effects of
network parameters on communication cycle times.
The network parameters can be specified from CX-Net in CX-Programmer or
the Controller Link Support Software. This section describes only the allow-
able setting range for each network parameter. Refer to the Controller Link
Support Software Operation Manual (W308) for setting procedures.
The following table shows the setting range and default for network parame-
ters.
Network parameter
Maximum node address
Number of polled nodes
Maximum number of event-frames
The network parameters become valid immediately after being set.
1. The default value is 32 for Optical Bus Networks.
2. The network parameters set at the polling node will be enabled. Therefore,
if there are multiple polling nodes, ensure that they all have the same set-
tings. If there are different settings, network operation will depend on the
polling node. Once the network has been constructed, however, the same
network parameters will be set for all nodes.
3. Always stop the data link before changing network parameters.
Setting range Default value
2 to 62 62 (See note 1.)
1 to 31 4
6 to 238 35
Section 9-1