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MELSEC-Q
6 PROGRAMMING
6.1.2 Program example
Interlocks should be applied to the programs according to the link status of the host
and other stations.
The following example shows an interlock in the communication program that uses the
link status of the host (SB47, SB49) and the link status of station number 2 (bit 1 of
SW70 and bit 1 of SW74).
(Example)
SB47: Host baton pass status
SB49: Host data link status
SB20: Network module status
SW70: Other station baton pass status
SW74: Data link status of each station
SW78: Other station parameter
communication status
Communication program with remote I/O station No. 2
Set the values shown below for timer constant K
.
Baton pass status
(T0, T2)
(Sequence scan time
4) or more
Cyclic transmission status
Parameter communication status
(T1, T3, T4)
(Sequence scan time
3) or more
Reason: This is to prevent occasional errors due to cable conditions or electrical noise
from stopping control.
Also, the multipliers of 4 and 3 should only be considered as a guideline.
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