Connecting
7.3 Connecting components
SIMATIC MV420 / SIMATIC MV440
Operating Instructions, 04/2013, A5E02371045-06
121
7.3 Connecting components
Connecting the 24 V DC power supply
WARNING
The device should only be connected to a 24 V DC power supply which satisfies the
requirements of safe extra low voltage (SELV).
When the device is operated on a wall, in an open rack or other similar locations, an NEC
Class 2 current source is required for the compliance of the UL requirements (according to
UL 60950-1). In all other cases (according to IEC/EN/DlN EN 60950-1), a current source
with limited power (LPS = Limited Power Source) is required.
24 V DC supply voltage (19.2 to 28.8 V)
The generation of the 24 V DC supply voltage by the line-side power supply must be
implemented as functional extra-low voltage with safe electrical isolation according
(floating) to IEC 80364-4-41, or as SELV to IEC/EN/DlN EN 60950-1 and LPS/NEC class 2.
CAUTION
Do not connect or disconnect cables when the power is on.
Note
Maximum ASM cable length
• You can use an ASM with the reader with a maximum cable length of 50 m.
• In some situations, longer connecting cables up to 1000 m are possible. In this case, take
into account the current consumption of the reader of 0.17 A for SIMATIC MV420 and
0.27 A for SIMATIC MV440.
• Avoid connecting more than two cable sections in series to create a longer cable due to
the connector resistance.
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