CalAmp GUARDIAN User Manual - page 18
Guardian Manual 001-5006-000 Rev 0
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2.2.2 POINT-TO-MULTIPOINT
A Point-to-Multipoint network is a common network type used in SCADA or other polling systems. The single
polling master station communicates with any number of remotes and controls the network by issuing polls and
waiting for remote responses. Individual PLC/RTU remotes manage addressing and respond when their individual
addresses are queried. PLC/RTU unit addresses are maintained in a scanning list stored in the host program or
master terminal device at the SCADA host site. Communications equipment is transparent and does not interact
with specific remotes; all data is coupled to the host on a single data line (such a network is commonly used with
synchronous radio modems and asynchronous radio modems).
Figure 2-2 – Point to Multipoint Network
2.2.3 MULTIPLE POINT-TO-POINT
A multiple point-to-point is similar to the point-to-multipoint system except the SCADA host has multiple serial
ports that are directed to different geographic areas in the SCADA system.
2.2.4 PEER-TO-PEER
A Peer-to-Peer network is generally used for device to device communications among a number of stations. This
network requires full addressing capability on the part of the data equipment (DTE). If the distances involved for
any link or links are too great for a single radio hop, they can be extended by means of repeaters without affecting
the basic network design.
2.2.5 STORE AND FORWARD
Store and Forward is a common technique where a data transmission is sent from one device to a receiving device
but first passes through a relaying device. The device is typically an RTU or PLC used by the message service to
store the received message then it transmits the message to the intended recipient.