5
5.6 Online Program Change for Redundancy
5.6.2 Program Change While CPU is Running
5
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1
OV
ER
VIE
W
2
SYS
TEM
CONFIGURA
TI
ON
3
TR
AC
KI
N
G
C
ABL
E
4
P
R
OCE
DURE
FO
R
S
TAR
TING
UP
A
RE
DUN
DAN
T
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
7
PR
OG
R
A
MM
IN
G
CA
UTIO
N
S
8
TR
O
U
BLE
S
HOOTING
However, even if the program of the new control system CPU module has not
been changed due to the system switching timing, the data calculated in the
previous control system after system switching may be tracked.
Diagram 5.68 Program and Device Data due to System Switching Timing
Control system
System A CPU module
Device
data
Program
Program
Perform write
during RUN
Standby system
System B CPU module
Device
data
Perform write
during RUN
Data before
changing
Data after
change
Data before changing
Data after change
If a system switching occurs in this zone, the System B
CPU module will perform control based on device data
calculated by the program after modification.