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Functionality |
This Driver must be used to operate in Slave mode, sending data to a DNP Driver in Master mode via Serial, Modem, or Ethernet TCP/IP.
Data sent to a Master through reading requests, usually commands for reading static variables or events, must be constantly informed to this Driver by writing to Tags, where each Tag must reference a point on a database.
For protocol's communication purposes, this Driver only recognizes the existence of a DNP object when the first value is written to an object. From this time on, the Master side can perform requests for this Driver, the Slave side, which then responds according to the requested objects.
NOTE |
Objects commonly read by the Master side, by using Function 1 for reading, must have their corresponding Tags registered on this Slave Driver with the N2 parameter equal to 1 (one), that is, writing this Tag to the Slave Driver informs an object's current value. Starting with this writing, this Driver checks whether the new value informed, when compared to the previous value, corresponds to an event generation, yet according to each Tag configuration, which is informed in the N1 parameter. |
For example, a Master requests the value of Object 1, Variation 2, and Index 100. This digital point must be registered on the Slave Driver's database using a Tag with the N1 parameter equal to 21 (assuming that this point generates a SOE and is linked to Class 1), the N2 parameter equal to 1 (one), the N3 parameter equal to 102, and the N4 parameter equal to 100. When starting the application, this point contains no value. By writing a value (zero or one) to this Tag, it is effectively created as an online point on this Driver's database.
NOTE |
An application, therefore, must always receive data from somewhere and set it to Tags on this Driver to update their values. |
For Tags to be declared as belonging to classes 1 (one), 2 (two), or 3 (three), with events with or without timestamp, when performing an attribution, an automatic check is performed to verify whether a new event must be generated, according to the dead band if they are analog or counters, setting this new event available to the class.
Even if the DeadBand property is declared as 0 (zero), users must perform a small change in value or quality to generate a new event. To prevent a dead band from checking, the value 100 can be added to the N1 parameter, according to the next examples.
•A Tag with the N1 parameter equal to 22 (SOE, Class 2), the N2 parameter equal to 1 (one), the N3 parameter equal to 3002, and the N4 parameter equal to 10 (16-bit Analog point 10, with SOE)
•Current value equal to 100, current quality equal to 192, and timestamp equal to 1/1/2012 12:00:00
Writing to this Tag with the same value and quality, but with a different timestamp in the configuration with the N1 parameter equal to 22, does not generate a new event.
But if the N1 parameter changes to 122, even if value and quality are the same, a new event is generated on writing. This is useful to represent trip events without a response or Sag/Swell events.