SIEMENS
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Siemens IC 10 · 2017
AS-Interface
Introduction
AS-Interface Specification
AS-i Power24V expansion
2
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Overview
AS-Interface data decoupling modules for AS-i Power24V
Picture left: S22.5 data decoupling module,
Picture right: DCM 1271 data decoupling module for SIMATIC S7-1200
Parallel wiring frequently dominates, above all, in applications
with very few I/Os. As the AS-Interface is also suitable for small
applications, the additionally necessary 30 V AS-Interface
power pack often also represents a cost barrier.
With the expansion of the AS-Interface to include AS-i Power24V
and the associated option of using the existing standard 24 V DC
power supply units in AS-i networks, the AS-Interface is now also
opened for extremely tightly calculated applications.
Data and power in standard AS-Interface networks up to now
One of the great advantages of AS-Interface is the ability to con-
vey not only data, but also the power needed for the connected
slaves and sensors over the same unshielded two-conductor
cable. This is owed to the service-proven AS-Interface power
supply units which provide integrated data decoupling as well
as overload and short-circuit protection and integrated ground-
fault monitoring.
The new technology
Through the expansion of AS-Interface with AS-i Power24V it is
now also possible to use 24 V standard power supply units in
AS-i networks. The communication technology of AS-Interface
works at the same high level of quality with an operating voltage
of both 30 V DC and 24 V DC.
Requirements for operation of an AS-i Power24V network
•
When 24 V power supply units are used, the maximum net-
work range of 50 m must be observed to reach slaves and
sensors with a sufficient level of voltage (at least 18 V).
•
The power supply units must comply with the PELV (Protective
Extra Low Voltage) or SELV (Safety Extra Low Voltage) stan-
dard, have a residual ripple of < 250 mV
pp
, and must limit the
output voltage to a maximum of 40 V in the event of a fault. We
recommend SITOP power supplies;
see page 15/1 onwards
.
•
When used in conjunction with standard 24 V power supply
units, each AS-Interface network requires AS-i Power24V-
capable data decoupling with adapted ground-fault detec-
tion;
see page 2/80
.
•
For reliable operation of an AS-i network with 24 V voltage, it is
important that the masters, slaves and other components are
approved for AS-i Power24V. AS-i Power24V-capable AS-i
components can also be used without restriction in standard
30 V AS-i networks.
•
Use of repeaters or extension plugs in AS-i Power24V
networks is not permitted.
■
Benefits
AS-i Power24V networks incur no additional costs for an
AS-Interface power supply unit because a pre-existing 24 V
power supply unit can be used. This brings the user several
benefits:
•
The level of standardization of very small applications can be
increased further.
•
The additional advantages of a modern communication sys-
tem in terms of commissioning, maintenance and diagnostics
can be fully exploited.
■
Application
Configuration of an AS-i Power24V network
Configuration of an AS-i Power24V network with an AS-Interface
DCM 1271 data decoupling module and S7-1200 (simple network)
■
More information
Key data of AS-i Power24V
Number of
slaves
Up to 62 standard slaves and up to 31 safe slaves
Topology
Any
Range
Up to 50 m
Components
• 24 V power supply unit with low residual ripple and
limitation to max. 40 V
• AS-i Power24V-capable data decoupling with integrated
ground-fault detection
• AS-i Power24V-capable masters, slaves and
components
More information
For a complete overview of AS-i Power24V-capable devices currently
available from Siemens,
see
For details of AS-i Power24V,
see "AS-Interface" system manual,
I/O modules
Up to 50 m
S7-1200 with DCM 1271, CM 1243-2
and 24 V standard power supply unit
AS-Interface
PROFINET
NSB0_02245a
© Siemens AG 2016