Overview of Modbus TCP protocol

MindSphere supports the Modbus protocol for the MindConnect IoT2040 and MindConnect Nano plugin. You can select the protocol type Modbus TCP while adding a new data source in Asset Manager.


Modbus configuration

The Modbus configuration view is only visible after a successful onboarding of the MindConnect IoT2040/Nano. The MindConnect Nano Version must be higher than V3.3.0.2.

The following picture shows the protocol selection in Asset Manager:


For more information about how to create a new data source see chapter Adding a data source and data points.

Modbus TCP data source parameter

In order to connect a Modbus TCP device, you need to select the Modbus TCP protocol and enter the following data source parameters:



IP Address

IP address of the Modbus device


Port number of the Modbus device (default: 502)

The following parameters are optional and can be adjusted for collecting data from slow Modbus devices:




You can set the timeout interval between two consecutive bytes of the same message received from the Modbus device. If the delay between is longer than the given timeout, an error will be generated. 


500ms (default) … 2000ms


You can set the timeout interval used to wait for a response from the Modbus device. If the waiting before receiving the response is longer than the given timeout, an error will be generated. 


500ms (default) … 60000ms


If a byte timout or a response timeout was detected, then this waiting time is added before the next request is started. During this time any response from the Modbus device will be flushed.


0ms … 45000ms. (default: 0ms)


You can set the time between the response from the Modbus device and the next request to this Modbus device. 


0ms (default) … 10000ms

Modbus TCP data point parameter

In order to collect the data of your Modbus TCP device, you must add new data points.

The following picture shows the data point parameter window:


The following table shows the parameter of the Modbus RTU data point window:



Data Type

Data type supported by backend (e.g. INT).

Function Type

Function type - depends on the type of the data (see manual of the Modbus device).

1: Read Coils

2: Read Inputs

3: Read Holding Registers

4: Read Input Registers

Currently function codes 1..4 are supported.

Slave Number

Address/Slave number of the Modbus device.

Start Address

Start address (offset) of the data.


Quantity of data to be read.


You can choose the following variable types of the Modbus data to be read:

1: char

2: unsigned char

3: short

4: unsigned short

5: long

6: unsigned long

7: float

8: double

9: ASCII-Text

Real Type

Real type - determines, if the registers of real values have to be processed in reversed order

0: Normal order

1: Reversed order

Response Address Offset

Offset of the data to return in register units.

Response Quantity

Quantity of the returned data. Only for string data  a value greater than 1 is supported.


TCP Gateway slave number

If you are using a TCP Gateway, you must select the appropriate slave number for the configuration of the data points.