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SCADA communication
Published in Mini S. Thomas, John D. McDonald, Power System SCADA and Smart Grids, 2017
Mini S. Thomas, John D. McDonald
The data received from the application process is the application data unit (ASDU), which contains the information objects format as given in Figure 3.10. The data link layer adds the link protocol control information (LPCI) to this data as header and footer from the link protocol data unit (LPDU). As can be seen, the message frame uses checksum error detection. The figure shows the variable length message frame structure LPDU where each block represents one character, the LPCI header with a start, length (message length), link control, link address (twice), and user data (ASDU) which can be up to 253 octets (8 bits) and the LPCI footer with checksum and end characters. Once the LPDUs are formed, the data are sent via the physical medium as octets.
A Data Communication Protocol for Building Automation and Control Networks: BACnet
Published in Viktor Boed, Ira Goldschmidt, Robert Hobbs, John J. McGowan, Roberto Meinrath, Frantisek Zezulka, of Facilities Automation Systems, 1999
Information from one controller or computer to another, via the BACnet protocol, is sent from the application program to the application layer of the protocol via an API. Network control, logical link control (LLC), and media access control (MAC) related parameters from API (i.e., identity address, protocol control information) go directly to the protocol’s network, data link, and physical layers. Application service-related parameters (primitives) go from the API to UE and ASE, generating application protocol data unit (APDU). The protocol data unit (PDU) is the data element of a network service primitive passed through the stacks of network layers.
From the Top Down: Channel Multiplex to Interleaver–Layer 2 and Part of Layer 1
Published in David P. Maxson, The IBOC Handbook, 2007
At 11 pages, the Layer 2 document is the thinnest of the NRSC-5 protocol documents, rivaled in brevity only by the AM and FM transmission system specification documents. Nevertheless, the Layer 2 document contains some key components of the structure of the digital information flow on IBOC signals. It addresses Logical Channels, content-based PDU structures, and “Protocol Control Information” embedded in its PDUs.
SCADA Research Lab Kit for Educational Institutes
Published in IETE Journal of Education, 2019
Lagineni Mahendra, Rajesh Kalluri, R.K. Senthil Kumar, B.S. Bindhumadhava, G.L. Ganga Prasad
Network access for IEC 60870-5-101 [4] using standard transport profiles is defined in IEC 60870-5-104 protocol. The length of the Application Protocol Data Unit (APDU) defines the length of the body of the APDU, which includes the four control field octets of the Application Protocol Control Information (APCI) and the Application Service Data Unit (ASDU) and is shown in Figure 4. Most of the type identifications of ASDU are defined IEC 60870-5-101standard and few new type identifications are defined in the IEC 60870-5-104 standard.