Siemens SINUMERIK 840D sl Function Manual page 171

03.06
Example:
The process quantity, e.g. hydraulic pressure, is switched using a standard valve
that is controlled in a safety-relevant fashion. A pressure sensor signals the status
of the process quantity. If the valve can no longer switch due to a fault condition,
then using a safely controlled standard contactor, the motor that is generating the
pressure, is shutdown. The advantage of this particular version is that components
can be used that are already available as standard. As to whether this solution can
be used, must be confirmed as a result of the risk assessment (see Fig. 7-4).
IM 151–1
F–DO
High Feature
PROFIBUS
with
PROFIsafe
When OK, only the valve
is switched. The pump
remains powered-up.
In the case of a fault, the
feedback signal from the
pressure sensor is
received, the pump motor is
additionally switched.
Fig. 7-4 Cascaded shutdown using fail-safe outputs
In other cases a second actuator must be connected in series in the load circuit
(see Fig. 7-5).
In conjunction with the safety-related control of a brake, no feedback signal is
available. The brake test will identify as to whether the actuator is correctly func-
tioning from a mechanical perspective.
© Siemens AG, 2006. All rights reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 03.2006 Edition
DI
PM–E F
Shutdown,
channel 1
Shutdown,
channel 2
not
Connecting Sensors/Actuators
7.1 Safety-relevant input/output signals
ET 200S PROFIsafe
Feedback signal
24 V load
circuit, valve
400 V load
circuit, motor
Feedback signal
Pressure
sensor
7-171