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Table 6- 58
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
6.12.5
Write and read 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
Table 6- 59
Transaction ID
Enclosed Drives
Operating Instructions, 12/2018, A5E36652151A
Access
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
6.12 Communication via MODBUS TCP
Unit
Scaling
ON/OFF text or
value range
-
-
-
-
-
-
-
-
Application Data Unit (ADU)
Length
2 bytes
Data / parameter
-
-
-
-
Protocol Data Unit (PDU
Unit ID
FCode
1 byte
1 byte
0 ... 252 bytes
Operation
-
-
-
-
Data
423
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