User Manual

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Siemens TX-I/O Engineering and installation guide CM110562en_13
Building Technologies Principles of electrical design 2019-05-15
10.6 Island bus expansion
10.6.1 Benefits of island bus expansion
• The island bus expansion modules allow for “decentralized” sub-islands with TX-I/O-
modules, that may be located up to 2 x 200 m from the "local" sub-island.
• The island bus expansion is based on differential RS-485 transmission technology.
• Programming / parameterization not required.
• The DIP switches for the bus master and bus terminator must be set correctly on the
island bus expansion modules.
• The island bus expansion is galvanically connected to the island bus (PTC protective
resistance of the
and ⊥ wires)
• The island bus expansion provides some protection against faults for sub-islands.
Example: A failed transformer in a decentralized sub-island (power AC 24 V for
power supply module), cannot result in a drop off of power (wire CS, DC 24 V) on
other sub-islands.
10.6.2 Limits
Number of decentralized sub-islands per I/O island
Max. 8
Number of island bus expansion modules per sub-island
Exactly 1
Number of I/O modules per I/O island
Maximum of 64
Number of I/O modules per sub-island No limit, as long as the
total of the entire island
(64) is maintained.
10.6.3 Restrictions
The island bus expansion operates as described here
– with TX-I/O modules for series C or higher only
– with P-Bus BIM series B or higher only
– with PXC-NRUD Series C and higher only (Migration – INTEGRAL AS1000)
– with all PROFINET BIM models
(see label packaging and device marking):
TX-I/O module P-Bus-BIM TXB1.PBUS PXC-NRUD
You may operate modules from series B as well as P-Bus-BIM series A with the island
bus expansion. The admissible length of the island bus expansion is the same as
described here, but the length of the island bus sections is reduced.
(see rule 23 on Page 92).
Note