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8.8.1
Cyclic transmission of when the submaster function is used
In cyclic transmission, data are periodically communicated among stations on the same network. Link devices (RX, RY,
RWr, RWw) are used for data communications. In the submaster function, the submaster station is performing data link
in case of disconnection of the master station; therefore, the submaster station can smoothly starts to take in control if
the master station is disconnected.
(1) Link device assignment of the master station and submaster station
Even if the control is shifted to the submaster station due to disconnection of the master station, the assignment
of areas for communications with the slave stations is the same as that of the master station; therefore, the same
program can be used for the master station and submaster station.
A send area for the master station allows information to be exchanged between the master station and the
submaster station.
Link device assignment is explained using the following example of when the station numbers 1 and 2 are slave
stations and the station number 3 is a submaster station.
Master operation
Station No.0
CPU module
Master
station
RX, RWr
Station
No.0
Station
No.1
Station
No.2
Station
No.3
RY, RWw
Range of the
station No.0
3
sending data
Range of the
1
sending data to
Sending
the station No.1
data
Range of the
sending data to
the station No.2
Range of the
3
sending data to
the station No.3
(a) Before the control is switched
• RY/RWw assignment
1
2
3
• RX/RWr assignment
4
5
Submaster
operation
Station No.3
Submaster
CPU module
station
RX, RWr
Station
No.0
Station
No.1
4
Station
No.2
Station
No.3
RY, RWw
Station
No.0
Range of the
1
sending data to
Sending
the station No.1
2
Range of the
data
sending data to
the station No.2
5
Range of the
station No.3
sending data
Data sent from the master operating station
Data sent from slave stations or submaster operating station
Create a program where sending data to the slave stations are the same in the master station
and submaster station.
Data is sent from the master station (master operating station) to the slave stations, not from
the submaster station (submaster operating station).
Data that is sent to the master station and data that is sent to the submaster station are stored
in RX/RWr of the submaster station.
Data that is sent from the slave stations is stored in the same area of the master station and
submaster station.
Data that is sent from the submaster station is stored in RX/RWr of the master station.
Station No.0
CPU module
Master
station
RX, RWr
Station
No.0
Station
No.1
Station
Switch
No.2
Station
Disconnected
No.3
RY, RWw
Range of the
station No.0
sending data
Range of the
sending data to
Sending
the station No.1
Range of the
data
sending data to
the station No.2
Range of the
sending data to
the station No.3
CHAPTER 8 FUNCTIONS
Master operation
Station No.3
Submaster
CPU module
station
RX, RWr
Station
No.0
Station
No.1
7
Station
No.2
Station
No.3
RY, RWw
Range of the
sending data to
the station No.0
Range of the
sending data to
Sending
the station No.1
6
data
Range of the
sending data to
the station No.2
Range of the
station No.3
sending data
Area where data is sent to other stations
181
8
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