Specifications

AS-Interface
Introduction
AS-Interface specification
AS-i Power24V expansion
6/5
Siemens IK PI · 2012
6
■ Overview
Symbol for AS-i Power24V
Parallel wiring often dominates still, particularly in applications
with very few I/Os. Although AS-Interface is similarly well suited
for small applications, its use is often prevented by the cost of
the 30 V AS-Interface power supply unit which is required in ad-
dition.
Through the expansion of AS-Interface with AS-i Power24V and
the resulting possibility of using existing standard 24 V DC
power supply units in AS-i networks, AS-Interface is now also
attractive for applications with a very tight budget.
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
• The maximum range of 50 m must be observed in order to
reach slaves and sensors with a sufficient level of voltage
(at least 20 V).
• The power supply units must comply with the PELV Standard
(Protective Extra Low Voltage) and have a residual ripple of
< 250 mVpp. We recommend power supply units from the
SITOP range, see Catalog IC 10.
• When used in conjunction with standard 24 V power supply
units, each AS-i network requires Power24V-capable data
decoupling with adapted ground fault detection.
• 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.
• The 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 an already 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
Construction of an AS-i Power24V network
Construction of an AS-i Power24V network with an AS-Interface S22.5
data decoupling module (simple network)
■ More information
A complete overview of AS-i Power24V-capable units currently
available from Siemens can be found at
http://support.automation.siemens.com/WW/view/en/42806066
Details of AS-i Power24V can be found in the
AS-Interface System Manual at
http://support.automation.siemens.com/WW/view/en/26250840
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
• 24V power supply unit with little residual ripple
• AS-i Power24V-capable data decoupling with integrated
ground-fault detection
• AS-i Power24V-capable masters, slaves and components
16$B
I/O modules
Up to 50 m
Single
data
decou-
pling
module
S7-300 with CP 343-2 / CP 343-2P
and 24 V standard power supply unit
AS-Interface
PROFINET
NSB0_02191a
Kap_06_en.book Seite 5 Freitag, 2. September 2011 1:42 13
© Siemens AG 2011