Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 247

7 APPLICATION FUNCTIONS
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POINT
(1) When a network is connected in a loop as shown in the figure below, make
sure to set the routing parameters so that the same relay station is routed for
both the "route from request source to request designation" and the "route
back from request destination to request source."
Do not set the destination and returning paths to circle the entire loop. The
first relay station in the return path from the request destination is determined
by the relay station in the forward path; thus, data cannot be transferred to a
station beyond that relay station and an error occurs.
Request
source
1
2 4
No.1
3
1
No.2
4
2
B
No.3
1
A
5
No.4
3 4
(2) When data is sent to a remote network by transient transmission using the
routing parameters, data is transferred through many networks; thus, the
amount of transmission data and the number of transmissions may affect the
entire system.
For example, in network number 2 to 5 in the figure above, the link scan time
may become temporarily longer and there may be delays in the transient
transmission of the local station because of the transient transmissions from
other networks.
When using the routing parameters, design the transient transmission by
considering the entire system.
(3) When multiple network systems are connected with the routing function, the
request source can send requests to destinations in up to eight network
systems (the maximum number of relay stations is seven stations).
A indicates the path from the request source to the
request destination.
B and C indicate the path from the request destination
to the request source.
Avoid path C when setting the return path.
No.8
3
C
2
No.7
1
1
Request
No.6
destination
3
2
No.5
MELSEC-Q
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