2 block formation and safety loops, 3 calculation – BECKHOFF TwinSAFE User Manual
Page 104

Circuit examples
102
Application Guide TwinSAFE
2.17.1 Parameters of the safe input and output terminals
EL1904 (applies to all EL1904 used)
Parameter
Value
Sensor test channel 1 active
Yes
Sensor test channel 2 active
Yes
Sensor test channel 3 active
Yes
Sensor test channel 4 active
Yes
Logic channel 1 and 2
Single Logic
Logic channel 3 and 4
Single Logic
EL2904
Parameter
Value
Current measurement active
Yes
Output test pulses active
Yes
2.17.2 Block formation and safety loops
2.17.2.1 Block 1
2.17.3 Calculation
2.17.3.1 PFH / MTTF
d
/B10
d
– values
Component
Value
EL1904 – PFH
1.11E-09
EL2904 – PFH
1.25E-09
EL6900 – PFH
1.03E-09
S1 – B10
d
1,000,000
S2 – B10
d
2,000,000
K1 – B10
d
1,300,000
K2 – B10
d
1,300,000
Days of operation (d
op
)
230
Hours of operation / day (h
op
)
8
Cycle time (minutes) (T
cycle
)
15 (4x per hour)
Lifetime (T1)
20 years = 175200 hours
K1
K2
EL1904
EL6900
EL2904
S1
S2
K1
K2
EL1904
EL6900
EL2904
S1
S2
EL1904