Siemens ISI EN 50295 Brochure page 8

AS-Interface
AS-Interface Safety at work
Introduction
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Overview
Safety included
The Safety at Work concept supports the direct integration of
components with relevance for safety, such as emergency stop
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switches, protective cover switches or safety light barriers, in the
AS-Interface network. These are fully compatible with the familiar
AS-Interface components (masters, slaves, power supply units,
repeaters, etc.) in accordance with EN 50295 and are operated
in conjunction with them on the yellow AS-i cable.
The signals from the safety sensors are evaluated by a safety
monitor. This not only monitors the switching signals of the safety
sensors but also continuously checks that data is being trans-
ferred correctly. The safety monitor has one or two release cir-
cuits in a two-channel configuration which can be used to bring
the machine or installation into a safe state. Sensors and moni-
tors can be connected at any point on the AS-Interface network.
It is also possible to use several monitors in the same network.
A failsafe controller or a special master is not necessary. The
master handles safety slaves in the same manner as all other
slaves and only receives the safety data for information pur-
poses. They can therefore be used to expand any existing
AS-Interface network.
Safety at Work guarantees a maximum response time of 40 ms.
This is the time between application of the signal to the input of
the safe slave and switching off the output at the safety monitor.
Tested safety
The system has been tested and approved by the German
Technical Inspectorate (TÜV). The transmission technique for
signals with relevance for safety is designed to allow applica-
tions to be implemented up to category 4 in accordance with
EN 954-1.
Software
The safety-related applications can be configured using the
configuration software and then transferred into the monitor.
Moreover, the software can also be used for online diagnostics.
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Benefits
• A failsafe PLC or special master is not required.
• Simple system structure due to standardized AS-Interface
technique.
• Safe and non-safe data on the same bus.
• Existing systems can be expanded quickly and easily.
• Safe signals can be combined in groups.
6/8 Siemens IK PI · 2004
• Integration of the safety signals in the plant diagnostics con-
cept.
• Approved up to category 4 acc. to EN 954-1.
• Safety at Work is certified by the German Technical Inspec-
torate (TÜV).
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Application
Integrated safety systems using AS-Interface can be used in ap-
plications for which EMERGENCY-STOP pushbuttons, protective
door locks, Stop category 0 and 1, two-handed operation and
light arrays are currently installed.
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Design
The safety system is constructed in the same manner as the now
familiar installation of AS-Interface.
The family of safe AS-Interface products comprises the safety
monitor that monitors the safe stations. The spectrum of safe sta-
tions comprises the safe modules and the safety-related sensors
with an integrated interface.
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Function
Following a master call, the safe stations transmit their informa-
tion, like the standard stations, to the master. The safety monitor
monitors this transfer from the safe stations to the master and
switches
• to the EMERGENCY-STOP status (in the case of faults in safe
stations) or
• to the safe status (in the case of a wire break).
The safety monitor is configured using software. The configura-
tion comprises the input signals of the safe stations and the in-
ternal functions of the safety monitor. The safety monitor offers
OR logic, AND logic, timer functions, buffer storage, etc.
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Integration
For integration of the safety system into AS-Interface, the exist-
ing infrastructure such as the master and the power supply unit
can continue to be used. For the safety system, the safety mon-
itor is integrated as a monitoring component and the safe station
is integrated as the interface between the safe sensors and the
system. The safe sensors can be used as before.