Omron DRT2 SERIES DEVICENET SLAVES - OPERATION MANUAL 04-2008 Operation Manual page 473

Remote I/O Communications Characteristics
8-1-4 System Startup Time
452
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 page 450 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.
This section describes the system startup time for a Network, assuming that
the scan list is enabled and that remote I/O communications are set to start
automatically at startup. The system startup time is the delay from the time
that the Master Unit is turned ON or restarted until the time remote I/O com-
munications begin.
The system startup time when the Master Unit is set to start up immediately
after power supplies of all the Slaves' are turned ON is different from when the
Master Unit is restarted while communications are in progress. The startup
times are shown in the following table.
Condition
The Master is
started immediately
after Slave startup.
The Master only is
restarted.
The Slaves only are
restarted.
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
Slave's indicator status
NS indicator is OFF or flash-
ing green.
NS indicator is flashing red
while the Master is OFF.
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Section 8-1
Group B
Master B
Slave f
Slave e
Group B
Master B
Slave f
Slave e
RM-B
System startup time
6 s
8 s
10 s