SIEMENS
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Siemens D 11 · 2015
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Function
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2
Highlights
Safety Integrated
Safe Speed Monitor (SSM)
The SSM function warns when a drive is working below an ad-
justable speed limit. As long as it remains below the threshold,
the function issues a safety-related signal.
Activation
If a speed value drops below a parameterized limit, a safety-re-
lated signal is generated. This can, for example, be processed
in a safety controller to respond to the event by programming,
depending on the situation.
Application
With the SSM function, in the simplest case, a safety door can be
unlocked if the speed drops below a non-critical level. Another
typical example is that of a centrifuge that may be filled only
when it is operating below a configured speed limit.
Customer benefits
Unlike SLS, there is no drive-integrated fault reaction when the
speed limit is exceeded. The safe feedback can be evaluated in
a safety control unit, allowing the user to respond appropriately
to the situation.
Safe Direction (SDI)
The SDI function ensures that the drive can only move in the se-
lected direction.
Activation
Deviation from the direction of motion currently being monitored
is detected reliably and the configured drive-integrated fault re-
action is initiated. It is possible to select which direction of rota-
tion is to be monitored.
Application
The SDI function is used when the drive may only move in one
direction. A typical application is to permit the operator access
to a danger zone, as long as the machine is rotating in the safe
direction, i.e. away from the operator. In this state, the operator
can feed material into the work zone / remove material from the
work zone without danger.
Customer benefits
The function saves the use of external components such as
speed monitors and the associated wiring. The release of a dan-
ger zone while the machine is moving away from the operator in-
creases productivity. Without the SDI function, the machine must
be safely stopped during material loading and removal.
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© Siemens AG 2015