9 Input Wiring Procedures
9.2 24 V DC input (Sink and source input type)
79
FX
3S
Series Programmable Controllers
User's Manual - Hardware Edition
1
Introduc
tion
2
Features an
d
Par
t N
am
es
3
Produc
t
Introducti
on
4
Specifi
cations
5
Ve
rsi
on and
Peri
pheral
De
vice
s
6
Sy
stem
Confi
gurati
on
7
Instal
lati
on
8
Preparati
on an
d
Pow
er Supply
Wi
ring
9
Input W
iri
ng
10
Hi
gh
-S
peed
Counters
3. In the case of input device with built-in parallel resistance
Use a device having a parallel resistance, Rp, of 15 k
Ω
or more.
If the resistance is less than 15 k
Ω
, connect a bleeder resistance, Rb (k
Ω
), obtained by the following formula
as shown in the following figure.
4. In the case of 2-wire proximity switch
Use a two-wire proximity switch whose leakage current,
, is 1.5 mA or less when the switch is off.
When the current is larger than 1.5 mA, connect a bleeder resistance, Rb (k
Ω
), determined by the following
formula.
Rb (k
Ω
)
≤
4Rp
15-Rp
Rp
Bleeder
resistance
Rb
PLC
(Sink input)
X
0V
24V
S/S
PLC
(Source input)
X
0V
24V
S/S
Rp
Bleeder
resistance
Rb
15 k
Ω
or more
15 k
Ω
or more
I
Rb (k
Ω
)
≤
6
I -1.5
Bleeder
resistance
Rb
PLC
(Sink input)
X
0V
24V
S/S
PLC
(Source input)
X
0V
24V
S/S
Bleeder
resistance
Rb
I
Two-wire
proximity sensor
I
Two-wire
proximity sensor