6
6-8
User manual IC220SDL953 - September 2011
GFK-2731
6.5
Two-channel assignment of safe outputs
For two-channel assignment of the safe outputs, two adjacent outputs are always used.
This assignment is fixed and cannot be parameterized (see "Two-channel" on page 5-2).
Figure 6-3
Two-channel assignment of outputs
K1 (R) and K2 (R) represent the positively driven N/C contacts for monitoring the state of
the relay (readback contacts). Connect these contacts via safe digital inputs. Evaluate the
readback and thus the state of the switching elements in your safety logic.
Basic specifications
WARNING: Loss of safety function
–
Connect the actuator ground directly to terminal point GND of the safety module. An
external ground may not be used.
–
The failure detection time is 20 ms. This means that high pulses of this width can
occur at the faulty output (channel) in the event of an error. The two-channel
assignment means that this does not result in a hazardous state.
73420006
K2 (R)
K1 (R)
K1
K2
OUT1_Ch1
GND
M
OUT1_Ch2
GND
Actuator
Two-channel
Achievable SIL/SIL CL/Cat./PL
SIL 3/SIL CL 3/Cat. 4/PL e
WARNING: Loss of electrical and functional safety
–
To achieve the specified safety integrity level, please refer to "Measures required to
achieve a specific safety integrity level" on page 6-3.
–
Please note that in order to achieve the specified PL, the actuator must have a
medium level of diagnostic coverage (90% to 99%) and medium MTTFd. A high level
of diagnostic coverage (> 99%) is recommended for the application according to
PL d.
–
Use actuators that can achieve the required safety integrity level.
–
Evaluate the readback contacts to achieve Cat. 3 or Cat. 4.
–
If the test pulses are disabled:
Test the outputs and external wiring by enabling the outputs at regular intervals. The
time between two tests must not exceed eight hours.