MOSCAD System Overview

The purpose of a MOSCADsystem is typically to provide some degree of automatic operation to a new or existing
customer process. The process may be found in water pump stations, sewage lift stations, communication system
monitoring, security, public notification control, electrical substation monitoring, distribution automation,
demand-side management, automated meter reading, or other applications. This automation is provided by a
mixture of hardware.
RTU: The field sites are equipped with MOSCAD
RTUs that collect data from on-site sensors, add data from
off-site sources, and use this data aggregate to make
decisions regarding how the process is operating. Changes
to the local process may be made; messages may be
initiated that send data elsewhere to influence the operation
of off-site equipment or to advise the SCADA Manager
of some important change.
Communications: The multiple sites in the system
may communicate among themselves by utilizing a variety
of communication choices: two-way conventional,
trunked, or MAS radio plus wire-line, fiber, microwave,
and satellite networks. MDLC is the signalling protocol
employed by MOSCAD, is based on the 7-layer OSI
recommendation, and is designed to be totally functional
on all of these communication media.
MDLC includes a store-&-forward capability that
permits different communication media links to be incorporated
into the total system, i.e. conventional radio and
trunked radio and microwave radio and wireline all interconnected
by MOSCAD into a single communication
system. Data may be passed from any site to any other site
in the system (peer-to-peer) either directly or by multiple
hops through intermediate MOSCAD sites. This peer-topeer
communication capability enables system designs
that use a distributed-intelligence operating philosophy;
central-intelligence-only systems may also be implemented
if the load on the communication system permits
it.
FEP: The Front End Processor is used at the central
site(s) to provide a two-way path to the communication system and the distant RTUs from the SCADA Manager
hardware & software. The FEP converts MDLC protocol data from the RTUs to a protocol used by the SCADA
Manager vendor: when the ModBus protocol is used, the FEP will maintain a local database of all the data from
the multiple in-field sites; when TCP/IP is used, the FEP is simply a gateway between the two different protocols.
The FEP always acknowledges all RTU-initiated messages. The FEP also provides a two-way path between the
MOSCAD Programming ToolBox and the field RTUs for those functions unique to MOSCAD that are not provided by the SCADA Manager software (over-the-air programming download, diagnostics upload, more).
SCADA Manager: The SCADA Manager provides the operator with the display and report tools necessary
to view and manage the associated process(es). The SCADA Manager obtains data from the FEP according to
its needs and typically presents that data on custom-created display formats; control messages may also be
initiated from these custom screens. Security is typically implemented via permission levels activated by the
operator’s sign-on password. Microsoft Windows is becoming the operating system of choice because it easily
supports the desired graphic symbols used on the custom screens. The report capability may be provided by the
SCADA software or a data export to Microsoft Excel or equivalent may be utilized. The end result is an easy to
use pictorally-described representation of the field status of key equipment items plus the means to make changes
in how those pieces of equipment operate.