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Modbus and DNP3 Communication Protocols


For the introduction of Modbus and DNP3 protocols, please refer to:

There are some open source projects or software/tools. Here are some for your reference.

For Modbus,

For the Modbus Master/Slave simulators:

For DNP3,

Community Member


A quick question.

I have a SCADA - RTU setup with DNP3 protocol for communication.

As per DNP3 specifications for Analog Input following flags will be updated.

2. Restart

3. Communications Lost

4. Remote Forced

5. Local Forced

6. OverRange

7. Reference Check

My Question is: who sets these flags? I mean whether SCADA (DNP Master) sets these flags against analog input or RTU (DNP Slave) sets these flags against analog input.

Community Member

All input only registers reflect the state of the corresponding physical entities.

So they are set by the slave and read by the master.

Typically master sets an input/output registrer as a control operation and the slave responds by performing some action. The result of the action could be read from some input register.

Community Member

check the micro service which provides REST/Websocket API for reading data from DNP3 slave/outstation

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