7
PROGRAMMING CAUTIONS
7.1 Instructions Restricted in Use for Redundant System
7
- 5
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
(4) SCJ Instruction
Note that jump processing for the specified pointer (P) varies with whether tracking
signal flow memory has been tracked or not, if the SCJ instruction contact turns ON
during system switching processing.
(a) When signal flow memory has not been tracked
Jumping is executed from the first scan after system switching.
(b) When signal flow memory has been tracked
Jumping is executed from the second scan or later after system switching.
Diagram 7.3 ON/OFF Operation of SCJ Instruction When Signal Flow Has Been Tracked
SCJ Instruction
Point
SCJ jump
(old control
system)
ON
OFF
Jump
Do not jump
SCJ jump
(new control
system)
Jump
Do not jump
Begin system switching
System switching
System Switching complete
After switching, Jump
from the first scan
(When Signal flow memory is not tracking)
SCJ Instruction
Point
SCJ jump
(old control
system)
ON
OFF
Jump
Do not jump
SCJ jump
(new control
system)
Jump
Do not jump
Begin system switching
System switching
System Switching complete
1 scan
After switching, Jump
from the second scan
(When Signal flow memory is tracking)