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3.4
Topologies in Local Security Network
Loop topology
Each LSN element provides a built-in isolator between the b1 and b2 connectors. The current
flows through the LSN element between b1 and b2. With the return of the current to the LSN
module the loop is formed. In normal operation, an LSN loop is powered alternatingly from
one or the other side (LSN1/LSN2) of the loop, and direction of the current flow changes each
10 seconds.
LSN classic
In a Local Security Network (LSN classic), LSN elements can be configured as a loop or as one
or two stubs. An LSN classic network allows a maximum of 127 elements.
LSN improved
An LSN improved network allows a maximum of 254 elements. With automatic address
setting, LSN elements can be configured as a loop or as one or two stubs. With manual
address setting, not only loop or stub, but also T-tap topologies are possible. As long as the
maximum number of 254 elements is not exceeded, the LSN improved network allows
branches anywhere along the LSN line, with any number of nodes, any number of branches
per node and any number of elements per branch. Consider, that mesh structures are not
allowed.
It is essential to ensure that no mesh structures are created.
Mesh structures within a stub
topology
Table 3.3: Examples for not allowed T-tap topologies
Notice!
i
Planning should take the anticipated total current and line resistance into account to ensure
each detector has an operating voltage of at least 15 V DC.
Notice!
In case of a bus fault, on stubs and branches no alternative way exists to reach an LSN
i
element. Since in a loop topology each element can be reached on an alternative way for
failure handling, prefer the loop topology.
Consider that regional authorities may require an upper limit to the number of elements that
can be lost due to a single fault.
Bosch Sicherheitssysteme GmbH
LSN 0300 A
LSN 1500 A
Mesh structures within a loop
topology
System manual
LSN 0300 A
LSN 1500 A
2022-07 | 5.0 | F.01U.378.910
Planning | en
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