DNP3 outstation port get closed when there is no actvity

[Faisal PEER MOHAMED]

Hi,

DNP3 outstation and master communication link is working fine.

If I close the master and restart, I can see the COMMS_DOWN AND COMMS_UP messages. This is perfect.

When I pull the cable from the master, I can't see the COMMS_DOWN message.

If I connect the cable back, the communication does not exis. It seems the port is closed by some means or master is not listening.

Any thoughts ?

Thanks,
Faisal

[Daniel Evans]

Faisal,

What level of logging do you have enabled? Try turning the logging up to DEBUG or COMM and pasting the results here.

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[Faisal PEER MOHAMED]

Thanks Daniel for the reply. It seems the problem is resulted from TCP Half open connection ( Physical connection (Ethernet cable) between dnp3 master and dnp3 outstation get disconnected after establishing successful connection. This situation will not occur during testing. It is expected in real time in case of loose connection).

This problem may be solved by sending a packet frequently from DNP3 outstation. In DNP3, by enabling unsolicited messages, the problem goes away. I have verified this.

In some cases I am not interested in unsolicted response. In that case how should we keep alive the TCP connection.

Thanks,
Faisal

[Daniel Evans]

Faisal,

Sorry for the late reply. I was able to confirm that a crash in the master will cause a quiet slave to not notice the socket is dead.  This will be fixed, either with a heartbeat in the data link layer or an idle timeout in the physical layer.