AccuEnergy Acuvim II series - Page 324

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6.4.4 Transport Layer
The pseudo-transport layer segments application layer messages into multiple
data link frames. For each frame, it inserts a single byte function code that
indicates if the data link frame is the rst frame of the message, the last frame of
a message, or both (for single frame messages). The function code also includes
a rolling frame sequence number which increments with each frame and allows
the receiving transport layer to detect dropped frames.
6.4.5 Application Layer
The Acuvim II Series Power Meter implementation supports a subset of the
objects and application layer function codes. The Acuvim II Series Power Meter
will neither accept nor send multiple fragment application layer messages. The
Acuvim II Series Power Meter’s fragment size is xed at 2k bytes.
Each application layer fragment begins with an application layer header
followed by one object header or object header and data combinations.
The application layer header contains an application control code and an
application function code. The application control code contains an indication
if the fragment is one of a multi-fragment message, contains an indication if
an application layer confirmation is requested for the fragment, contains an
indication if the fragment was unsolicited, and contains a rolling application
layer sequence number. The application layer sequence number allows the
receiving application layer to detect fragments that are out of sequence, or
dropped fragments.
In the Acuvim II Series Power Meter, the DNP3.0 supports the Read function , the
Direct Operate function and the Direct Operate Unconrmed function.
The Read function ( 0X01 )
The read function is the basic code used for requesting data objects from an
Outstation. Here this function is used for reading the measurement data from