Point-To-Multipoint; Multiple Point-To-Point; Peer-To-Peer; Store And Forward - CalAmp Guardian User Manual

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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 7 Point to Multipoint Network

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.

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.

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.

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Guardian™ Serial Modem or Analog Radio for Licensed Spectrum PN 001-5006-000 Rev. 3

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