Mitsubishi Electric MELSEC iQ-R Series User Manual page 59

■Data link error of the standby system
The following table lists cases in which systems fail to be switched due to a data link error in the standby system.
System System switching cause of
switching control system
method
Automatic Moderate error or major error
system
switching
Reset or hardware failure
Data link error
Manual System switching operation using
system the engineering tool
switching
*1 Depending on the content of the major error, the remote head module of the control system may not switch to the standby system.
System status before
and after the system
switching cause occurs
*1
Remote head No.1: Control
system  Standby system
Remote head No.2: Standby
system  Control system
Remote head No.1: Control
system  
Remote head No.2: Standby
system  Control system
Remote head No.1: Control
system  Control system
Remote head No.2: Standby
system  Standby system
Remote head No.1: Control
system  Control system
Remote head No.2: Standby
system  Standby system
Status after powering off and on remote head No.2 after
eliminating the cause of failure to switch systems
Remote head No.1: 
Remote head No.2: Control system
Since remote head No.1 is faulty, remote head No.2 starts as the
control system.
Remote head No.1: 
Remote head No.2: 
Systems do not start.
Remote head No.1: Control system
Remote head No.2: Standby system
Since remote head No.1 is normal, remote head No.2 starts as the
standby system.
Remote head No.1: Control system
Remote head No.2: Standby system
Since remote head No.1 is normal, remote head No.2 starts as the
standby system.
1.8 Redundant Function
1
1 FUNCTIONS
57