Descriptions of functions
10.8 Communication via Modbus TCP
SINAMICS DCM DC Converter
Operating Instructions, 12/2018, A5E34763375A
543
Table 10- 49 Assignment of the Modbus register for general parameter access using DS47
Register Description
Access Unit
Scaling
ON/OFF text
or Value range
Data / parameter
40601
DS47 Control
R/W
-
-
-
-
40602
DS47 header
R/W
-
-
-
-
40603
DS47 data 1
R/W
-
-
-
-
…
…
40722
DS47 data 120
R/W
-
-
-
-
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
10.8.4
Read and write access using function codes
Function codes used
For data exchange between the controller and device, 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
Figure 10-56 Individual components, including the Modbus Application Header (MBAP) and function
code
