Omron DeviceNet 3G8F7-DRM21-E, Руководство по эксплуатации

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112
Remote I/O Communications Characteristics
Section 6-1
T
OH
: Protocol overhead
T
BYTE-IN
: The input byte transmission time
B
IN
: The number of input bytes
T
BYTE-OUT :
The output byte transmission time
B
OUT :
The number of output bytes
For Input Slaves use B
OUT
= 0, and for Output Slaves use B
IN
= 0.
6-1-2 More than One Master in Network
This section explains how to calculate the remote I/O communications cycle
time (T
RM
) when there is more than one Master in the Network. In this exam-
ple there are two Master Units in the Network.
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.
Note The Slaves are physically separated into two groups for clarity in this diagram,
but the actual physical positions in the Network are irrelevant.
Next, we refer to the equations introduced in 6-1-1 Communications Cycle
Time and calculate the communications cycle time for each group as if they
were separate Networks.
In a Network with two Masters, the communications cycle time for the entire
Network is the sum of the communications cycle times for the two groups.
T
RM
= T
RM-A
+ T
RM-B
Baud rate T
OH
T
BYTE-IN
T
BYTE-OUT
500 kbps 0.306 ms 0.040 ms 0.036 ms
250 kbps 0.542 ms 0.073 ms 0.069 ms
125 kbps 1.014 ms 0.139 ms 0.135 ms
Group A
Master A
Slave A Slave B Slave C
Group B
Master B
Slave D Slave E Slave F
Slaves in remote I/O commu-
nications with Master A Slaves in remote I/O commu-
nications with Master B
Master A
Group A
Slave A Slave B Slave C
Group B
Master B
Slave D Slave E Slave F
Group A communications
cycle time: T
RM-A
Group B communications
cycle time: T
RM-B