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134
Message Communications Characteristics
Section 7-2
Program Example
As shown in the preceding table, it takes time for DeviceNet communications
to start up. This programming uses flags in the Master Status Area to prevent
the slaves' I/O processing from being performed until the Master Unit and
remote I/O communications have started up.
Note
Refer to the operation manual of the Master Unit being used for details on the
Master Unit Status Area.
The following program example is for a CS/CJ-series PLC and a Master Unit
with a unit number of 00.
7-2
Message Communications Characteristics
7-2-1
Message Communications Time
The message communications time is the time required from the time a Mas-
ter Unit starts to send a message over the Network to another node until the
Master Unit completes sending the message (SEND/RECV instructions to
send/receive data and CMND/IOWR instructions to execute FINS com-
mands).
Note
If the CPU Unit attempts to send another message or receives a message
from another node before the message communications time has finished, the
response message being sent or the message being received from another
node may be destroyed. Always perform message communications at inter-
vals longer than the message communications time and use message instruc-
tions (SEND, RECV, CMND, and IOWR). Never send messages to any one
node at intervals less than the message communications time.
If send or receive messages are destroyed, the error record will be placed in
the error history of the Master Unit. If an error occurs, read the error history
using the FINS command or monitor the error history from the Configurator.
The following equation can be used to calculate the approximate message
communications time.
Message communications time = Communications cycle time
×
((No. of mes-
sage bytes + 15) ÷ 6 + 1)
The master only is
restarted.
NS indicator is flashing red or green
while the master is OFF.
8 s
The slaves only are
restarted.
-
11 s
Condition
Slave's indicator status
System startup
time
(004)
JMP #0001
(005)
JME #0001
2001
15
2001
14
I/O Data
Communications
Flag
Error/
Communications
Stopped Flag
Slave's I/O
processing
Содержание EJ1 - 07-2008
Страница 1: ...DeviceNet Communications Unit for EJ1 Temperature Controllers Cat No H155 E1 02 OPERATION MANUAL...
Страница 2: ...DeviceNet Communications Unit for EJ1 Temperature Controllers Operation Manual Revised July 2008...
Страница 3: ...iv...
Страница 19: ...xx...
Страница 33: ...14 Initial Temperature Controller Settings Section 1 4...
Страница 53: ...34 Wiring the Temperature Controllers Section 3 4...
Страница 101: ...82 Ladder Programming Examples Section 4 6...
Страница 143: ...124 Sending Explicit Messages Section 6 5...
Страница 155: ...136 Message Communications Characteristics Section 7 2...
Страница 163: ...144 Maintenance Section 8 2...
Страница 189: ...170 Allocation Numbers for Configurators Manufactured by Other Companies Appendix B...
Страница 197: ...178 Index...