More Than One Master In Network - Omron E5ZN-DRT Operation Manual

Remote I/O Communications Characteristics
7-1-3

More than One Master in Network

Note The number of words refreshed is the total number of words in the I/O Area
that are allocated to the slaves, including any unused words between those
words actually used by the slaves.
For example, if there are only two Input Slaves with node addresses 1 and 5,
the 5 input words for nodes 1 through 5 would be refreshed even though the
input words for nodes 2, 3, and 4 are unused.
If message communications are being performed, just add the number of
words used in message communications to the above number of words for
whenever messages are being processed.
The following equation shows the communications cycle time (T
there is more than one master in the Network.
An example for two Master Units is shown here.
First, the Network is divided into two groups: Master A and the slaves in
remote I/O communications with it, and Master B and the slaves in remote I/O
communications with it.
Group A
Master A
Slave a
Slave b
Slaves in remote I/O
communications with Master A
Note Although in the above diagram the slaves are separated into two separate
groups for each master for convenience, the actual physical positions of the
slaves in the Network are irrelevant.
Next, refer to 7-1-2 CompoWay/F Communications Cycle Time and Refresh
Time and calculate the communications cycle time for each group as if they
were separate Networks.
Group A
Master A
Slave a
Slave b
Communications cycle time for
Group A: T
RM-A
In Networks with two masters, the communications cycle time for the entire
Network will be the sum of the communications cycle times for both groups.
T = T
RM RM-A
Although this example shows only two masters in the Network, the total com-
munications cycle time for any Network with more than one master can be cal-
culated by dividing it into groups performing remote I/O communications and
adding the communications cycle times of all the groups.
Slave c
Slave d
Slaves in remote I/O
communications with Master B
Slave c Slave d
Communications cycle time for
Group B: T
+ T
RM-B
Section 7-1
Group B
Master B
Slave f
Slave e
Group B
Master B
Slave f
Slave e
RM-B
) when
RM
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