222 Fieldbus Communication
WAGO-I/O-SYSTEM 750
750-880, 750-880/025-000 ETHERNET Programmable Fieldbus Controller
Manual
Version 1.0.1
Pos: 109.8 /Alle Serien (Allgemeine Module)/Feldbuskommunikation/MODBUS/Anwendung der MODBUS-Funktionen - Einleitung @ 7\mod_1265623985585_21.doc @ 49940 @ 33 @ 1
12.2.2 Use of the MODBUS Functions
The example below uses a graphical view of a fieldbus node to show which
MODBUS functions can be used to access data of the process image.
Highbyte
Lowbyte
0x000
3
0x000
2
0x000
1
0x0000
0x000
5
0x000
4
0x000
7
0x000
6
0x000
8
0x000
1
0x0000
0x000
3
0x000
2
0x000
5
0x000
4
0x000
7
0x000
6
0x0009
0x000
8
Wor
d2
Wor
d2
Wor
d2
Wor
d1
Wor
d2
Wor
d2
Wor
d2
Wor
d1
Wor
d2
Wor
d2
Wor
d2
Wor
d1
Wor
d2
Wor
d2
Wor
d2
Wor
d1
Wor
d2
Wor
d2
Wor
d2
Wor
d1
Wor
d2
Wor
d2
Wor
d2
Wor
d1
Wor
d2
Wor
d2
Wor
d2
Wor
d1
Wor
d2
Wor
d2
Wor
d2
Wor
d1
0x000
3
/ 0x0
2
0
3
0x000
2
/ 0x0
2
0
2
0x000
1
/ 0x0
2
0
1
0x0000 / 0x0
2
00
0x000
4
/
0x0
2
0
4
0x0
2
0
3
0x0
2
0
2
0x0
2
0
1
0x0
2
00
0x0
2
0
4
0x0000 / 0x0
2
00
0x000
1
/ 0x0
2
0
1
0x0
2
00
0x0
2
0
1
1
1
2
1
2
3
1
3
2
3
AO
DO
AO
750-34
2
O
N
LINK
Tx
D
/
R
x
D
I/
O
E
RROR
Ethernet
W
A
G
O
ß
I/
O
ß
S
Y
S
TE
M
DI DI
DI
DI DI
AI AI
AI
AI
Highbyte
Lowbyte
Highbyte
Lowbyte
Ei
ng
a
ng
s
k
lemme
n
75
0
- 4
00
4
00
467 467 4
00
467 4
00
4
00
467
F
C
3
(
)
(
Read I
n
put Re
g
iste
r
s)
Read Multiple Re
g
iste
r
s
F
C
4
M
O
D
BU
S-Ad
r
esse
n
F
C
1
(
Read I
n
put Disc
r
etes)
Read
Co
ils)
F
C
2
(
M
O
D
BU
S-
Ad
r
esse
n
Aus
g
a
ng
s
k
lemme
n
75
0
- 5
0
1 55
0
55
0
F
C
6
(
)
F
C
16
(
Multiple Re
g
iste
r
s)
Wr
ite Si
ng
le Re
g
iste
r
Wr
ite
M
O
D
BU
S-Ad
r
esse
n
F
C
3
(
Read I
n
put Re
g
iste
r
s)
Read Multiple Re
g
iste
r
s)
F
C
4
(
M
O
D
BU
S-Ad
r
esse
n
M
O
D
BU
S-Ad
r
esse
n
F
C
1
(
Read I
n
put
)
Read
Co
ils)
F
C
2
(
Disc
r
etes
M
O
D
BU
S-Ad
r
esse
n
F
C
5
(
Co
il)
F
C
15
(
F
or
ce Multiple
Co
ils)
Wr
ite
Figure 80: Use of the MODBUS Functions