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Siemens TX-I/O Engineering and installation guide CM110562en_13
Building Technologies Safety guidelines 2019-05-15
2.4 Specific regulations for TX-I/O devices
2.4.1 Safety notes for engineering
If you are responsible for the control-panel engineering, you should check that you
have access to the documents listed in Section 1.3. Observe the engineering notes and
safety regulations in these documents.
2.4.2 Wiring safety notes
Type
Electrical isolation
Relay outputs Electrically isolated
The insulation resistance between one relay output and
another, and between the relay outputs and SELV/PELV,
is AC 3750 V in accordance with EN 60730. The relay
outputs are suitable for double or reinforced insulation.
Adjacent I/O points may, therefore, have different
voltages (a mixture of mains and low voltage is
permitted).
I/O island
All TX-I/O devices of an I/O island are electrically connected.
Direct island bus
integration (PXC3...)
Desigo TRA: the PXC3... room automation station and the
I/O island are electrically connected (AC 24 V GND is
connected to island bus GND).
Direct island bus
integration
PXC100...,
PXC200...)
Desigo: the PXC....D automation station and the I/O island
are electrically isolated. The island bus driver of the
automation station is supplied by the I/O island.
Integration via P-Bus
BIM
P-bus and island bus are electrically connected (G0 and ⊥).
Integration via
PROFINET BIM
Island bus and PROFINET BIM are electrically connected.
The BIM is electrically isolated from the PROFINET (Ethernet
bus) and all the devices connected to it (PCs, S7).
Island bus expansion
Island bus and island bus expansion are electrically isolated
(via a PTC protective resistor)
• All low-voltage terminals of all TX-I/O products are interchangeable and may be
short-circuited against system neutral without damaging the electronic circuitry.
• However, the error should be fixed as soon as possible.
• There is no protection against incorrectly wired external voltages from the
field devices (e.g. AC 230 V).
Electrical isolation
Protection against
incorrect wiring of
AC/DC 24 V