Communications - Motorola V186 - Cell Phone - GSM System Planner Manual

Communications

The ACE3600 (as well as MOSCAD family RTUs) facilitates the establishment of a
highly sophisticated hybrid data communication network for SCADA that utilizes a
variety of radio and/or line communication links. Radio links may include conventional
(VHF, UHF, 800 & 900 MHz), analog trunked, digital trunked, and both analog and
digital microwave radio technologies. Line links may include point-to-point, multi-drop,
Public Service Telephone Network (PSTN) voice/data via dial-up modems, cellular
packet data modems and Local Area Networks (LAN).
Multiple data bit rates are available to accommodate the particular need of these links.
Lower data speeds are used when the bandwidth of the link is reduced either by their
design or by laws in the user's country, or when data speed is sacrificed to achieve
greater communication range. The higher data speeds typically usable, combined with the
optimized-for-radio MDLC data protocol, ensure high network throughput even if the
network is spread over a large geographical area.
The ACE3600 system network consists of RTUs communicating with one or more
computerized control centers and/or with other RTUs. Each control center is connected to
the communication network.
The system can be relatively simple, comprising several RTUs and one control center. It
can be modularly expanded to a more hierarchical system, where several sub-systems
(comprising intelligent RTUs and/or sub-centrals controlling their peripheral RTUs)
communicate with a central computer.
The communication network is flexible, enabling each RTU to communicate with
hierarchies above it (RTU-to-central), parallel to it (RTU-to-RTU), under it (another
RTU), and also relaying messages through it (when the RTU serves as a communication
node).
While the communication protocol allows for a complex hierarchical system structure, it
does not make it complicated. This is because most of the communication interactions are
transparent to the user, except in those cases where the communication is to be defined by
the user program ladder application. In such cases, you should perform simple
programming operations to configure the required application.
Each RTU may be configured to serve as a far-end terminal or as a regional center. The
RTU may function as a regional center either by definition or only after loss of
communication with the central. It also can act as a communication node (an
interconnection point between two or more different links) while performing its other
tasks.
The RTU network uses the MDLC protocol, which incorporates all seven layers of the
OSI model adapted for SCADA. It supports multiple logical channels per physical port,
enabling simultaneous central-to-RTU and RTU-to-RTU sessions. It also enables each
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