94
Function Description
WAGO-I/O-SYSTEM 750
750-880, 750-880/025-000 ETHERNET Programmable Fieldbus Controller
Manual
Version 1.0.1
Pos: 75.37 /Serie 750 (WAGO-I/O-SYSTEM)/Funktionsbeschreibung/Datenaustausch/Datenaustausch - Datenaustausch MODBUS/TCP-Master und Busklemmen @ 6\mod_1256049861734_21.doc @ 43310 @ 3 @ 1
7.3.3
Data Exchange between MODBUS/TCP Master and I/O
Modules
Data exchange between the MODBUS/TCP Master and the I/O modules is
conducted using the MODBUS functions implemented in the controller by means
of bit-by-bit or word-by-word reading and writing routines.
There are 4 different types of process data in the controller:
• Input
words
• Output
words
• Input
bits
• Output
bits
Access by word to the digital I/O modules is carried out in accordance with the
following table:
Table 36: Allocation of digital inputs and outputs to process data words in accordance with the
Intel format
Digital inputs/
outputs
16. 15. 14. 13. 12. 11. 10. 9. 8. 7. 6. 5. 4. 3. 2. 1.
Process data
word
Bit
15
Bit
14
Bit
13
Bit
12
Bit
11
Bit
10
Bit
9
Bit
8
Bit
7
Bit
6
Bit
5
Bit
4
Bit
3
Bit
2
Bit
1
Bit
0
Byte
High byte D1
Low byte D0
Output can be read back in by adding an offset of 200
hex
(0x0200) to the
MODBUS address.
Note
Data > 256 words can be read back by using the cumulative offset!
All output data greater than 256 words and, therefore located in the memory range
0x6000 to 0x62FC, can be read back by adding an offset of 1000
hex
(0x1000) to
the MODBUS address.
