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FS-8700-47 DNP 3.0 Driver Manual Page 27 of 51
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• If required sets flags for
• Map Descriptor matching,
• fetch/store function calls
• and/or response function call
• Signals Chan idle the outgoing app layer message needs to be processed.
Master Idle
• Looks for signals from chan idle that a message has been received
• Processes Map Descriptors and forms read/write messages
• Signals Chan idle the outgoing app layer message needs to be processed.
Appendix A.5. DLL Layer Functionality in the Master
The DNP Primer provided by dnp.org describes the DLL layer requests for confirmation as optional
and suggests that it is not often employed. Our driver never asks for DLL layer confirmations. Thus
the DLL layer functions as a mere wrapper/unwrapper layer. It wraps user data with a header and
CRC's but does not perform node-node confirmations.
The only DLL layer functions which have been implemented are send and respond with user data and
link reset. The slave DNP driver will not respond until a link reset has been performed. The DNP
master driver sends a Link Reset request when a Map Descriptor requests data from an un-reset
node. The link resetting is performed on a node-node link.
Appendix A.6. App Layer Functionality in the Master
The App layer provides over 40 app layer functions, confirmations and responses and allows for
handling of a huge number of data objects.
1. Read
2. Write
3. Select
4. Operate
6. Direct Operate with no Ack (limited)
8. Direct Freeze with no Ack (limited)
129. Response
App Layer
Functions
130. Unsolicited. (Slave Driver can parse these messages.)
Internal
Indications
The Slave indicates its internal state by appending internal indication bytes to the
app layer header of each response. Thus it can report that it is faulty, corrupted or
unable to process the request. If it can’t find a matching Map Descriptor it sets the
internal indication bit used to indicate that the data object parameters specified
cannot be parsed.
You can configure a Server node to respond with the internal indications bytes that
are extracted from a Data Array allowing you to control them. For more
information, refer to Error! Reference source not found..
App Layer
Qualifier
The app layer contains a Qualifier Byte used to control indexing for data objects.
The DNP 3.0 Driver only handles Qualifiers 00, 01, 07, 08, 17, 28. Qualifier 6 is
supported with limitations.
App Layer
Confirmation
The DNP 3.0 (master) Driver never asks for an App Layer Confirmation. The DNP
3.0 Slave Driver is capable of responding to an app layer request for confirmation
(to allow it to process an unsolicited message which may ask for confirmation.)