Standby Master Function - Mitsubishi Electric MELSEC iQ-R Series User Manual

1.3

Standby Master Function

If the master station goes down due to an error in a CPU module, power supply, or others, switching the control to the standby
master station (a backup station for the master station) can continue data link. This function is used not to stop the entire
system even if the master station goes down.
Type
The standby master function can be categorized into three types as listed below.
: Enabled, : Disabled
Function
Master station
switching function
Master station duplex
function
Data link startup
function using a
standby master
*2
station
*1 A standby master station does not start data link until the master station starts up.
*2 Configure the same system for the master station and standby master station (same modules connected, module parameters, and
program).
Operation
The following are the operations of the master station and standby master station of when the master station goes down.
The following figure shows the operation from when the master station goes down and the standby master station continues
data link to when the failed master station goes back to normal.
Controlling: Controlling the data link of the CC-Link system
Standby status: Standing by in case the station controlling the data link of the CC-Link system becomes faulty.
Data link control by the master station
Master station
Controlling
Master station is down
Master station
*1 The dot matrix LED indicates the station number set in the module instead of "0". The MST LED turns on and the S MST LED turns off.
1 FUNCTIONS
42
1.3 Standby Master Function
When the master station
goes down, the standby
master station
continues data link.



Remote device station
(station No.: 2, number of
occupied stations: 2)
Cyclic transmission
Data link control by the standby master station
Remote device station
(station No.: 2, number of
occupied stations: 2)
Cyclic transmission
When a failed master When only a standby
station becomes normal master station is started
again, it returns in case up, it starts data link.
of the standby master
station going down.
 
 
 
Intelligent device station
(station No.: 4, number of
occupied stations: 1)
Cyclic transmission
Intelligent device station
(station No.: 4, number of
occupied stations: 1)
Cyclic transmission
To the next figure
"Station Type" in "Required
Settings"
Master
station
*1
Master Station
*1
Master Station
(Duplex
Function)
Master Station
(Duplex
Function)
Standby master station
(station No.: 1, number of
occupied stations: 1)
Cyclic transmission
Standby master station
(station No.: 1→0
Controlling
Cyclic transmission
Standby
master
station
Standby Master
Station
Standby Master
Station
Master Station
(Duplex
Function)
*1
)