5
5.6 Online Program Change for Redundancy
5.6.2 Program Change While CPU is Running
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OV
ER
VIE
W
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SYS
TEM
CONFIGURA
TI
ON
3
TR
AC
KI
N
G
C
ABL
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P
R
OCE
DURE
FO
R
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TAR
TING
UP
A
RE
DUN
DAN
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S
Y
S
T
E
M
5
RE
DUNDA
NT S
Y
S
T
E
M
FUNCTIONS
6
RE
DUN
DAN
T
S
Y
S
T
E
M
NE
TW
O
R
K
S
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PR
OG
R
A
MM
IN
G
CA
UTIO
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8
TR
O
U
BLE
S
HOOTING
(a) When SM1710 is OFF (Default)
When SM1710 is off, tracking will be suspended until online program change is
complete.
If a system switching occurs during online program change, the new control
system CPU module may output old data.
For example, if output (Y) is turned on in the control system during online program
change, the output (Y) on information will not be tracked to the standby system
CPU module since tracking has not been performed.
If system switching occurs under these conditions, output will turn on and off at
the time of the system switching.
Diagram 5.66 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
OFF
ON
Abort tracking transfer due to run write operation
requested from within GX Developer
M0
Y100
M0
Y100
Refresh to the network
module
Control system Standby System
M0
Y100
M0
Y100
Standby system Control System
M0
Y100
M0
Y100
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
Set Y100 external
output to ON
System B CPU
module's Y100
external output will be
set to off because
Y100 is OFF.
Circuit is added to
System B CPU
module
Set Y100 external
output to ON
When M0 is set to
ON in the System
B CPU module,
When a system
switching occurs,
the output
undergoes
chattering
Refresh to the network
module
Perform system switching due to a stop error in the control CPU module