77
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
4 Devices in Detail
4.4 State Relay [S]
1
In
troduct
io
n
2
Ov
e
rv
ie
w
3
In
st
ru
ct
ion
Li
st
4
D
evi
ce
s
in
De
ta
il
5
Speci
fied t
h
e
D
evi
ce &
C
onst
a
nt
6
Bef
o
re
Pr
ogr
a
m
m
ing
7
Bas
ic
In
st
ru
cti
o
n
8
FNC0
0
-FNC0
9
P
ro
g
ra
m F
lo
w
9
FNC1
0
-FNC1
9
M
ov
e
&
C
om
par
e
10
FNC
20-
FNC
2
9
Ar
ith.
&
Logi
c
O
per
at
io
n
4.4
State Relay [S]
State relays (S) are important devices to program stepping type process control simply, and combined with
the step ladder instruction STL.
State relays can be used in the SFC (sequential function chart) programming method.
→
For programming by the step ladder instruction and SFC method, refer to Chapter 34.
4.4.1
Numbers of state relays
The table below shows state relay (S) numbers. (Numbers are assigned in decimal.)
*1.
This area is not latched (battery backed). It can be changed to the latched (battery backed) area by
setting parameters.
*2.
This area is latched (battery backed). It can be changed to non-latched (non-battery-backed) area by
setting parameters.
*3.
The characteristics of latch (battery backup) cannot be changed by parameters.
4.4.2
Functions and operation examples
1. General type
In the stepping type process control shown in the left
figure, when the start signal X000 turns ON, the state
relay S20 is set (turned ON) and the solenoid valve
Y000 for moving down turns on.
When the lower limit switch X001 turns ON the state
relay S21 is set (turned ON) and the solenoid valve
Y001 for clamping turns on.
When the clamp confirmation limit switch X002 turns
ON, the state relay S22 is set (turned ON).
When the operation proceeds to the next step, the
state relay in the preceding step is automatically reset
(turned OFF).
When the PLC turns OFF., all of general type state
relays are turned OFF.
When the ON/OFF status just before power failure is
required, use latched (battery backed) type state
relays.
State relays have many NO contacts and NC contacts in the same way as
auxiliary relays, and such contacts can be used arbitrarily in sequence
programs.
When state relays (S) are not used for step ladder instructions, they can
be used in general sequences in the same way as auxiliary relays (M) (as
shown in the figure on the right).
General type
latched (battery
backed) type
Fixed latched (battery
backed) type
Annunciator type
FX
3U
/FX
3UC
PLC
S0 to S499
500 points
(S0 to S9 are provided
for initial.)
*1
S500 to S899
400 points
*2
S1000 to S4095
3096 points
*3
S900 to S999
100 points
*2
S 2
S 20
S 21
S 22
Start
Lower
limit
Clamping
Upper
limit
Initial state
TRAN
Start
X000
Y000
Moving down
TRAN
Lower limit
X001
Y001
Clamping
TRAN
Clamping
X002
Y002
Moving up
TRAN
Upper limit
X003
X001
S10
S10
M30
Y005