Mitsubishi Electric MELSEC-Q Series User Manual page 148

(c) ON/OFF timing of link special relays (SBs) related to the standby master function
The following figure shows the ON/OFF timing of link special relays (SBs) related to the standby master
function.
Host master/standby master operation status
Master switching request acknowledgement
Master switching request complete
Refresh instruction at standby master switching
Refresh instruction acknowledgement status
at standby master switching
Refresh instruction complete status
at standby master switching
*1 When turning on Master switching request acknowledgement (SB005A), save data stored in RX, RY, RWr, and RWw to
the devices and set data stored in RX to RY, data stored in RY to RX, data stored in RWr to RWw, and data stored in
RWw to RWr using a program. In addition, turn on Refresh instruction at standby master switching (SB0001).
After saving data stored in RX, RY, RWr, and RWw to the devices, wait a fixed number of scans and execute the
processing that sets data stored in RX to RY, data stored in RY to RX, data stored in RWr to RWw, and data stored in
RWw to RWr using a program and the processing that turns on the Refresh instruction at standby master switching
(SB0001).
For details, refer to Page 143, Section 8.2.5 (5).
146
Master station information
OFF
(SB0070)
ON
(SB007B)
OFF
(SB005A)
OFF
(SB005B)
(Program operation)
OFF
(SB0001)
OFF
(SB0042)
OFF
(SB0043)
ON
OFF
ON
*1
ON
ON
ON
ON