Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 375

7 APPLICATION FUNCTIONS
System switching monitoring
time setting valid instructed
System switching monitoring
time setting invalid instructed
7 - 151
(2) System switching monitoring time
Set the time between an error occurring in the own station data link status (The D.
LINK LED turns off.) and a system switching request issued using SW0018
(System switching monitoring time setting).
For details of SB and SW, refer to Appendices 3 and 4.
Set value
0 (default)
*1
1 to 500
*1: This set value is valid when the system switching monitoring time setting valid flag
(SB0018) is on.
To reduce the system switching monitoring time from 2 seconds (default) to 0.5
seconds, set SB0018 and SW0018 in the sequence program as shown below.
POINT
The network module issues a system switching request through the process
described in (1) of this section and automatically switches the systems of the
redundant system.
However, if the standby station has been already in an error status (power supply
off, redundant CPU resetting, stop error, etc.), the system will not be switched even
if the network module issues a system switching request to the control system
CPU.
For details, refer to the QnPRHCPU User's Manual (Redundant System).
Monitoring time before issuing a system switching request
A system switching request is issued 2 seconds after SB0049 turns
on.
A system switching request is issued (set value x 10 ms) after
SB0049 turns on.
MELSEC-Q
Sets 0.5 seconds for system switching
monitoring time.
Makes SW0018 setting valid.
Makes SW0018 setting invalid.
7 - 151