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5.6 Online Program Change for Redundancy
5.6.2 Program Change While CPU is Running
5
(b) When SM1710 is ON
When SM1710 is on, if a system switching occurs, old data will not be output
because tracking is performed also during online program change.
(Refer to Section 5.5.4 for tracking data settings.)
Diagram 5.67 Operation When System Switching Occurs during Online Program Change
M0
Y100
Control system
System A CPU module
M0
Y100
M0
Y100
M0
Y100
Standby system
System B CPU module
OFF
ON
M0
Y100
M0
Y100
Refresh to the network
module
Control system Standby System
M0
Y100
M0
Y100
M0
Y100
M0
Y100
Standby system Control System
M0
Y100
M0
Y100
Refresh to the network
module
Refresh to the network
module
Circuit before
program change in
ladder mode during
RUN
Y100
external
output
Circuit is added to
System A CPU
module
When M0 is set to
ON, Y100 is also
set to ON
Due to tracking
M0, Y100 will be
set to ON
Set Y100 external
output to ON
System B CPU
module's Y100
external output will be
left ON because Y100
is ON.
Circuit is added to
System B CPU
module
Refresh to the network
module
Perform system switching due to a stop error in the control CPU module