Mitsubishi QJ71LP21 Reference Manual page 206

7 APPLICATION FUNCTIONS
Link special relay and link special register used for setting a system switching monitoring time
Number
SB0018 Switching monitoring time setting
enable flag
SW0018 Switching monitoring time setting
System switching monitoring
time setting enable directive
System switching monitoring
time setting disable directive
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The network module issues a system switching request when the status of data link is
changed from "under data link" to "data link halted." (when the D.LINK LED of the
network module turns off.)
Although the time interval from when the data link is stopped to when the system
switching request is issued to the QnPRHCPU is set to two seconds, the interval can
be changed using the link special relay SB and link special register SW.
To issue the system switching request immediately after detecting that data link is
stopped, reduce the system switching monitoring time.
However, note that a system switching request is issued frequently if the network is not
stable and the system switching monitoring time is reduced too much.
Name
To reduce the system switching time from 2s to 0.5s, set SB0018/SW0018 in the
sequence program as follows.
1: If SB0018 is disabled (OFF), the system switching monitoring time is 2s (default).
POINT
The network module issues the system switching request to the QnPRHCPU even
when the data link error is caused by the following accident: the network module
mounted in the control system is not connected with a cable or disconnected at the
time of power ON.
The network module issues the system switching request within 4s after power ON.
Indicates whether the switching monitoring time setting is enabled or
disabled.
OFF : The switching monitoring time setting (SW0018) is disabled.
ON : The switching monitoring time setting (SW0018) is enabled.
Set a time from the detection of a data link halt to issue of system
switching request in the redundant system.
0: 2s (default)
1 to 500: in 10ms (set up in 10ms units within the range of 10ms to 5s.)
MELSEC-Q
Description
Set up a system switching time of 0.5s.
Enable the SW0018 setting.
Disable the SW0018 setting. 1
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