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8-5
Remote I/O Communications Performance
Section 6-1
Com
m
uni
ca
tions
P
e
rfor
m
a
nce
Next, calculate the communications cycle time for each group referring to 6-1-
2 Communications Cycle time and Refresh Processing Time .
The communications cycle time for the overall network when there are two
masters will be as follows:
T
RM
= T
RM-A
+ T
RM-B
Although this example uses a network with only two masters, the same
method can be used for any number of masters. Simply divide the network up
according to remote I/O communications groups and then add all of the com-
munications cycle times for the individual groups to calculate the communica-
tions cycle time for the overall network.
System Startup Time
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.
Group B Group A
Master A
Slave a Slave b Slave c
Master B
Slave d Slave e Slave f
Group A communications cycle time: T
RM-A
Group A communications cycle time: T
RM-B
Condition Slave's indicator status System startup
time
The master is started immedi-
ately after slave startup. NS indicator is OFF or flashing
green. 6 s
The master only is restarted. NS indicator is flashing red while
the master is OFF. 8 s
The slaves only are restarted. --- 10 s