Write And Read Access Using Function Codes - Siemens SINAMICS G130 Operating Instructions Manual

Operation
6.11 Communication via MODBUS TCP
Table 6- 49 Assignment of the Modbus register for general parameter access using DS47
Register Description
40601 DS47 Control
40602 DS47 header
40603 DS47 data 1
... ...
40722 DS47 data 120
Note
Limited value range
Modbus TCP registers have a maximum 16 bit width. The values of display parameters (r
parameters) cannot always be represented with 16 bits. In these particular cases, the
maximum value that can be represented is displayed.
• Unsigned: 65535
• Signed min: -32768
• Signed max: 32767
6.11.5

Write and read access using function codes

Function codes used
For data exchange between the master and slave, predefined function codes are used for
communication via Modbus.
The Control Unit uses the following Modbus function codes:
● FC 03: Holding register to read data from the inverter
● FC 06: Write single register to write to individual register
● FC 16: Write to multiple registers to write to several registers
Structure of a Modbus TCP message
Table 6- 50
Transaction ID
304
Ac-
cess
R/W
R/W
R/W
R/W
Individual components, including Modbus Application Header (MBAP) and function code
Modbus Application Header
Protocol ID
2 bytes 2 bytes
Unit Scaling ON/OFF text
or Value range
- -
- -
- -
- -
Application Data Unit (ADU)
Length
2 bytes
Operating Instructions, 07/2016, A5E00331449A
Data / parameter
- -
- -
- -
- -
Protocol Data Unit (PDU
Unit ID FCode
1 byte 1 byte 0 ... 252 bytes
Inverter chassis units
Data