DNP3 unsolicited messages on P139

[ManuelTrebilcock]

Hi everyone,

I want to know where you enable unsolicited messages on  Easergy MiCOM P139.

Best regards,

Manuel Trebilcock

[AndreMelo]

Hi @ManuelTrebilcock 

I didn't find the P139 DNP3.0 profile documentation but in DNP3 a parameter to put the UNsolicited on/off is rarely needed cause this control is made by the Master.  At the end of the day, you can easily check that using a protocol simulation and sending an ENABLE_UNSOLICITED. 

In DNP3, the Device Profile has different implementation levels, which means that some functions can be supported or not, as well as have fixed values or configurable.

Said that we need to know the difference between Unsolicited ON/OFF and Enable and Disable.

Unsolicited Enable/Disable:

In DNP3 when the communication starts the Outstation (IED slave) that has Unsolicited capabilities. Will send to the Master a NULL_UNSOLICITED  that indicates to the Master that it supports unsolicited.

Then if the Master wants/supports unsolicited messages, it will send to the IED an ENABLE_UNSOLICITED (DNP3 Function CODE 20) and waits for the confirmation. An from that point on, the IED will start to send Unsolicited messages.

When the Master wants to close the communication or not receive Unsolicited anymore, It sends a DISABLE_UNSOLICITED (DNP3 Function CODE 21).

Unsolicited ON/OFFparameter:

Unsolicited "ON" doesn't mean that the device will send Unsolicited messages - ON means that the device will behave like it has it implemented.

Unsolicited "OFF" means that the Device will behave like if it hasn't it implemented.

To summarize, this parameter is barely needed cause if the Device supports unsolicited, it will wait until the Master enables it before sends the Unsolicited message, and if the Outstation does not support it, it won't send the NULL indication, and the Master will not try to enable it.