Mdlc Protocol - Motorola V186 - Cell Phone - GSM System Planner Manual

RTU to simultaneously run several kinds of communication applications, such as
reporting alarms by contention, on-line monitoring, performing diagnostics checks, etc.
The MDLC protocol is discussed below.

MDLC Protocol

The MDLC protocol is a Motorola SCADA protocol that is based on the Open System
Interconnection (OSI) model recommended by the International Organization for
Standardization. MDLC utilizes all seven layers of the OSI model. This protocol is
designed for optimum operation in SCADA systems which operate with diverse
communication media such as two-way radio, line, LAN, etc. Each RTU, FEP, or
ToolBox has all seven layers of the MDLC protocol available to them. The functions of
the seven layers are summarized below.
Layer Function
This layer caters to communications over conventional radio, trunked radio,
Layer 1:
data radio, serial data channels, modems, Ethernet or telephone lines. The layer
Physical
is also responsible for channel access and collision control on shared media.
This layer ensures proper communications over a physical link. The layer
Layer 2: Link
arranges the data in variable-length frames and attaches addresses, frame
sequence numbers, and Cyclic Redundancy Code (CRC) to the frames.
This layer is responsible for the establishment of end-to-end communication
Layer 3.
paths in a network. This is necessary since communications may take place on
Network
more than one link and a message may travel through several nodes before
reaching the final destination.
This layer ensures end-to-end integrity of the information flow between two
Layer 4.
nodes in the network. This is achieved by remote-end acknowledgement that
Transport
data has been received completely and passed in the correct order to the next
layer.
This layer allows the definition of any number of entities capable of
Layer 5.
Session conducting simultaneous sessions with an equivalent entity in some remote
unit. This enables transparent communications among multiprocessing
machines without interference in their applications.
This layer structures the information to/from various applications. This layer
Layer 6.
Presentation may also perform format conversion, data authentication, etc. if implemented.
This layer interfaces to the various applications such as data transfer,
Layer 7.
Application configuration downloading, application software monitoring, remote
diagnostics, etc.
The MDLC protocol is intended for operation in point-to-multipoint links, such as two-
way radio or multidrop wireline, as well as in point-to-point communication networks.
The protocol facilitates communications among all sites in the system, including
extensive diagnostic messaging. MDLC is transparent and liberates the system engineer
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Communications