User Manual

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Siemens TX-I/O Engineering and installation guide CM110562en_13
Building Technologies Wiring 2019-05-15
System ground (⊥) is connected in this case, since ⊥ serves as a common return.
If a sub-island is powered by its own transformer, it may be earthed separately. If it is
not earthed, an equalization wire must be installed.
For earthing details and examples of the island bus expansion see section 10.6.6.
Transformer phasing
There is no need to take account of the relationship between the transformer phases.
This means different phases (L1, L2, L3) can be used for the transformer supply.
Separate power supply
for each I/O row
This may be necessary or advisable for
– Two I/O rows separated by a long distance
– High power-demand at the I/O modules (actuators)
6.4.2 Wiring for the island bus (module supply DC 24 V)
Cable materials
• The requirements for the CS and CD conductors (communication supply and
communication data) of the island bus are as follows:
– 2-core round cord without shield
– Single cables are not admissible, either inside or outside the control panel.
Notes
• Flat cord is admissible, but the EMC-immunity is lower than with round cord.
• The island bus can be extended to a length of 100 m by using coaxial cable
(see Section 10.5).
Maximum cable lengths
For details refer to Section 10.5.
Routing of the bus cable
• The bus cable MUST be routed together with the supply cable AC 24 V (see wiring
examples in Section 6.5.2). Both are part of the bus connection.
• In principle, the bus connection MAY be routed together with with AC 3 x 400 V
conductors.
Howerver, to maintain electromagnetic compatibility, we recommend that low
voltage conductors be separated from mains conductors. Recommended minimum
clearance: 150 mm.
Caution: Low voltage conductors that are routed adjacent to mains conductors
must have the same insulation rating as the mains conductors.
Bus topology • Serial wiring and a "star" configuration are admissible.
To this end, the relevant terminals on the power supply modules are available in
duplicate and interconnected internally (see Section 3.4, "TXS1.12F10 power
supply module and TXS1.EF10 bus connection module").
• The bus must not be wired in a ring configuration.
Only ONE bus master
per I/O row
• Never connect more than one bus master via the same island bus.
Definition: One I/O island = all modules that are connected to the same island bus
segment, i.e. to the same bus master.
Only one island bus
connection per I/O row
• The CD conductor may be connected once only for each I/O row.
It is not permissible, when using two power supply modules, to connect two bus
trunks to one I/O row (this would create a ring configuration!).
System neutral (
⊥
) • The bus needs ⊥ in addition to the CS and CD conductors.
• This conductor is routed together with AC 24 V.
See the examples below and the illustration in Section 6.4.