Satel SATELLINE-EASy Guida Utente Scaricare il pdf (Pagina 79)

SATELLINE-EASy Pro

User Guide v.1.5

10.3.3 Repeater chain using dual addressing

If the terminal devices cannot add address chains to the beginning of the data packets, a network

with several repeaters may still be realised by using dual addressing. In dual addressing each link

(see arrows below in figure) is given a unique address, which will prevent duplication of messages

and endless loops in the network. The terminal devices need not add anything to the data.

Usually the primary transmit address is used in transmission (TX1). The secondary transmit address

(TX2) is used only if the Repeater Mode is used and the packet to be repeated was received using

the secondary reception address (RX2).

In the following example two repeaters are used. It should be noted that each link (arrow) might

be uniquely defined with the help of radio modem numbers and data transfer directions. The

Repeater Mode should be switched ON only in the radio modems acting as repeaters to prevent

the packets from remaining in endless loops in the network.

Repeaters may also act as ordinary substations; in that case the terminal device must wait until the

message has reached the end of the repeater chain before sending data.

10.3.4 Redundant repeater chain

Reliability of a radio data communication system can be improved significantly by designing

redundant equipment setup for master and repeater stations. The two repeater chains are

separated by proper dual addressing setup. Slave stations need to be able to communicate with

the master through the both repeater chains. By using the "TX address auto switch" function, the

slave station modem directs the reply message to the repeater chain from which the request has

been received.

If "TX address auto switch" has been set ON, radio modem checks out the RX address of the

received message. When one of the RX addresses is recognised, all the messages coming in from

the serial interface will be sent to the air with matching TX address. The use of "TX address auto

switch" function is not recommended if Repeater Function is set ON.

(12)

(21)

(43)

(34)

rxd

txd

rxd

txd

Modem 1

master

Modem 2

repeater

Modem 3

repeater

Modem 4

TX1

RX1

TX2

RX2

Addresses:

1 2 ... 74 75 76 77 78 79 80 81 82 83 84 ... 103 104

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Satel SATELLINE-EASy Guida Utente Pagina 79

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