User manual

IEC61131 User and Reference Manual
April 22, 2008
447
Pseudo-Transport Layer Breaks the application layer messages into smaller packets that can
be handled by the data link layer. These packets are referred to as
frames in DNP.
Data Link Layer Handles the transmission and reception of data frames across the
physical layer.
Physical Layer This is the physical media, such as serial or Ethernet, which DNP
communicates.
These layers are described in the following sections of this manual.