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MELSEC-Q
7 APPLICATION FUNCTIONS
7.4 Multiplex Transmission Function (Optical Loop System)
Master Remote
The multiplex transmission function allows high-speed communications using duplex
transmission paths (both the forward and reverse loops) in the optical loop system.
In order to execute the multiplex transmission function, setting for the "Supplementary
settings" of the common parameters is required. Note that this setting is not allowed
unless the total number of link stations is four stations or more.
(1) Using the multiplex transmission function, the high-speed communication is
performed using both the forward and reverse loops effectively.
1MR
1R5
1R1
1R4
1R2
1R3
Forward loop
Reverse loop
IN
OUT
IN
OUT
IN OUT
OUT
IN
OUT
IN
OUT
IN
(2) If an error occurs in the transmission path while the multiplex transmission function
is used, data linking continues by communicating only using the transmission path
on one side of either the forward or reverse loop, or by switching to the
communication using loopback. The transmission speed in this case is 10
Mbps/25Mbps.
1MR
1R5
1R1
1R4
1R2
1R3
Forward loop
Reverse loop
Loopback
Down
Loopback
IN OUT
OUT IN
IN OUT
OUT IN
IN OUT
OUT IN
REMARKS
The multiplex transmission function is effective only in reducing the link scan time
when the number of connected stations is 16 or more and the link devices assigned
with common parameters is 2,048 bytes or more. The link scan time will be 1.1 to
1.3 times faster compared to when the multiplex transmission function is not used.
If the multiplex transmission function is used in the configuration where the number
of connected stations or the assigned link devices is less than the above, the link
scan time may be increased compared to the case where the function is not used.