WAGO 750-830 Manual page 216

216 • Fieldbus Communication
MODBUS Functions
4.3.2 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.
FC 3 (
1 1
3
Fig. 4-16: Use of the MODBUS Functions
Attention
It is recommended that analog data be accessed with register functions (1) and
digital data with coil functions (2).
DI DI AI AI
Ethernet
ON
LINK
TxD/RxD
ERROR
I/O
Input modules 750- 402 402 472 472 402 476 402 476
Read Multiple Registers )
FC 4 (Read Input Registers)
MODBUS addresses
0x0000 Word2 Word1
0x0001 Word2 Word2
0x0002 Word2 Word1
0x0003 Word2 Word2
0x0004 Word1 Word2
0x0005 Word2 Word2
0x0006 Word1 Word2
0x0007 Word2 Word2
0x0008
Highbyte Lowbyte
FC 1 ( Read Coils)
FC 2 ( Read Input Discretes )
MODBUS
addresses
0x0000
0x0001
0x0002
0x0003
0x0004
2
0x0005
0x0006
0x0007
0x0008
0x0009
0x000A
0x000B
0x000C
0x000D
0x000E
0x000F
DI
AI DI AI
Output modules 750- 501 550 550
FC 6 (Write Single Register
FC 16 ( Write Multiple Registers)
MODBUS addresses
0x0000 / 0x0200 Word2 Word1
0x0001 / 0x0201 Word2 Word2
1
0x0002 / 0x0202
Word2 Word1
0x0003 / 0x0203
Word2 Word2
0x0004 /
3
0x0204
Highbyte Lowbyte
FC 3 ( Read Multiple Registers)
FC 4 ( Read Input Registers)
MODBUS addresses
Word2 Word1
0x0200
Word2 Word2
0x0201
1
0x0202
Word1 Word2
0x0203
Word2 Word2
3
0x0204
Highbyte Lowbyte
FC 5 (Write Coil)
FC 15 (Force Multiple Coils)
MODBUS addresses
0x0000 / 0x0200
2
0x0001 / 0x0201
FC 1 ( Read Coils)
FC 2 ( Read Input Discretes)
MODBUS addresses
0x0200
2
0x0201
AO
DO AO
)
WAGO-I/O-SYSTEM 750
BACnet/IP Controller
G012918e