7
PROGRAMMING CAUTIONS
7.1 Instructions Restricted in Use for Redundant System
7
- 3
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
• Program example
Diagram 7.2 shows a program that reads data from the intelligent function
module on the remote I/O station by the REMFR instruction.
2) The instruction that includes no execution completion signal or write instruction
needs to be executed again, as it is difficult to determine if its execution is
completed or not.
However, note that the same instruction might be executed twice.
Diagram 7.2 Example of REMFR instruction programming
Turns ON M202 when system
switching occurs during execution
of the REMFR instruction.
Turns ON M201 to execute the
REMFR instruction when M200 or
M202 is ON, the MELSECNET/H
remote I/O network is normal, and
normal communication can be
made with the remote I/O station
of Station No. 10.
Turns OFF M200 to M202 on
completion of the REMFR
instruction execution.
Processing at abnormal completion
SM1518
SM1518
SM1518 M203
M204
M204
SB20 SB47 SB48 SB49 SW70.9 SW74.9 M203
M200
M202
M201
M201
0
3
35
SET
M202
SET
M201
K0
Z.REMFR "j1" K1 K10 H1 H100 D200 K10 M203
K0
RST
M200
RST
M201
RST
M202
Processing at normal completion
