An outstation can indicate with the internal indication IIN1.1, IIN1.2 or IIN1.3 that class data is available for event class 1, event class 2 or event class 3 respectively. According to the standard a DNP3 master shall immediately send a read request for event class data when one or more of these flags is set. If however this flag remains active for a prolonged period of time, and is not reset by the outstation, even though the master has successfully read the event class data, the DNP3_NG driver continues to send read requests for event class data and any other requests (read or write) are dropped from the send queue.
An outstation can indicate with the internal indication IIN1.1, IIN1.2 or IIN1.3 that class data is available for event class 1, event class 2 or event class 3 respectively. According to the standard a DNP3 master shall immediately send a read request for event class data when one or more of these flags is set. If however this flag remains active for a prolonged period of time, and is not reset by the outstation, even though the master has successfully read the event class data, the DNP3_NG driver continues to send read requests for event class data and any other requests (read or write) are dropped from the send queue.
The DNP3_NG driver has been enhanced with a new option to ignore the internal indication flags IIN1.1, IIN1.2 and IIN1.3. When this option is enabled, the DNP3_NG master driver no longer sends spontaneous read requests for event class data, and instead continues polling for event class data as per the cycle time configured in the driver configuration. With this option enabled, the DNP3_NG driver communicates to legacy hardware that does not timely clears the internal indication bit after the master reads the event class data, and allows the DNP3_NG driver to send regular read and write requests.
implemented with driver version 60x, available from version 7.00 SP0 build 5