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...5 MODBUS FUNCTIONS
5.3 Force Single Coil – Function Code 05
5.3.1 Force Single Coil Query
This message forces a single coil either ON or OFF. The data value 65,280 (FF00 HEX) sets the coil
ON and the value zero turns it OFF. All other values are illegal and have no effect on coil status.
Note. To write to a coil its offset address (one less than the coil number) must be used, e.g.
to write to coil 39, the coil address 38 (26H) is transmitted.
The use of slave address zero (broadcast mode) forces all attached slaves to modify the desired coil.
Example. Switch ON coil address 39 (auto/manual state) in slave 01.
A
d
d
e r
s
s
F
u
n
t c
0
1
0
5
5.3.2 Force Single Coil Response
The response is confirmation of the query after the coil state has been altered.
Example
A
d
d
e r
s
s
F
u
n
t c
0
1
0
5
12
C
o
l i
S
a t
t r
O
o i
n
H
g i
h
0
0
C
o
l i
S
a t
t r
O
o i
n
H
g i
h
0
0
f
s f
t e
D
a
a t
L
o
w
H
g i
h
2
6
F
F
f
s f
t e
D
a
a t
L
o
w
H
g i
h
2
6
F
F
V
a
u l
e
E
r r
r o
L
o
w
0
0
6
D
V
a
u l
e
E
r r
r o
L
o
w
0
0
6
D
C
h
e
c
k
F
e i
d l
(
C
R
C
1
) 6
F
1
C
h
e
c
k
F
e i
d l
(
C
R
C
1
) 6
F
1
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