Specifications

AS-Interface
Introduction
Transmission technology
6/2
Siemens IK PI · 2009
6
■ Overview
The AS-Interface is an open, international standard in accor-
dance with EN 50295 and IEC 62026-2 for fieldbus communica-
tion. Leading manufacturers of actuators and sensors worldwide
support AS-Interface. The electrical and mechanical specifica-
tions of the AS-Interface Association are made open to inter-
ested companies.
The AS-Interface is a single master system. For automation sys-
tems from Siemens, there are communications processors (CPs)
and network transitions (Links) that function as masters to con-
trol process or field communication as well as sensors and actu-
ators that are accessed as AS-Interface slaves.
■ Benefits
An important characteristic of the AS-Interface technology is the
use of a common two-core cable for data transmission and
distribution of auxiliary power to the sensors and actuators.
For distributing the auxiliary power, an AS-Interface power sup-
ply is used which satisfies the requirements of the AS-Interface
transmission procedure. The AS-Interface cable is mechanically
coded which prevents polarity reversal during wiring, and the
insulation displacement methods allows easy contact.
Complex control cable wiring in the control cabinet and terminal
blocks can be replaced with AS-Interface.
Thanks to a specially developed cable and insulation displace-
ment technology, the AS-Interface cable can be connected any-
where.
This concept results in enormous flexibility and significant cost
savings.
■ Function
Operating modes
In general, the following operating modes are distinguished with
the master interface modules:
I/O data exchange
In this operating mode, the inputs and outputs of the binary
AS-Interface slaves are read and written to.
Analog value transmission
AS-Interface master in accordance with AS-Interface specifica-
tion V2.1 or V3.0 support integral analog value processing. This
makes data exchange with analog AS-Interface slaves (in accor-
dance with analog profile 7.3 or 7.4) as easy as with digital
slaves.
Command interface
As well as I/O data exchange with binary and analog AS-Inter-
face slaves, the AS-Interface masters provide a range of other
functions using the command interface.
Thus for example, slave addresses can be allocated, parameter
values can be transferred or diagnostics information can be
read out from user programs.
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