Mitsubishi MELSEC-Q Series User Manual page 185

8 PROGRAMMING
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(4) Link special registers (SW)
The link special registers store the data link status using word data.
Buffer memory addresses 600
SW0000 to SW01FF.
For more details on the link special registers (SW0000 to SW01FF), see Section
8.4.2.
(5) Random access buffer
The random access buffer stores any data to be sent to other stations.
The reading and writing of data are performed using transient transmission.
(6) Communication buffer
The communication buffers stores the send and receive data when performing
transient transmission (communication using the communication buffers)
between the local stations, standby master station, and intelligent device stations.
The communication buffer sizes for the local station, standby master station, and
intelligent device station are set with network parameters.
For more details on the communication buffer size settings, see Section 6.2.
[Example of communication using the communication buffers]
Master station
CPU
RIRD
Receive
buffer for the
first module
1) Accesses the buffer memory of the local station or the device memory of the
CPU.
2) Stores the data specified by the control data in the receive buffer for the first
module.
Master station
CPU
Send buffer
1)
RIWT for the first
module
1) Stores the data to be written in the buffer memory of the local station or to the
device memory of the CPU in the send buffer for the first module.
2) Accesses the buffer memory of the local station or the device memory of the
CPU.
to 7FF correspond to link special registers
H H
Local station (first module)
CPU
1)
Device memory
1)
2)
2)
Local station (first module)
CPU
2)
Device memory
2)
MELSEC-Q
Buffer memory
Buffer memory
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