Product · Safety functions (PL & SIL)
Define and verify safety functions: PL and SIL
Calculate PL and SIL next to the hazard they address, not in a separate tool.
- Achieved PL ≥ PLr check per function
- PFHd shown per subsystem
- Calculation report export
How you do it in MSA
5 steps
- 1
Define the safety function
Link it to the hazards it reduces and describe the safe state.
- 2
Determine PLr
Walk the ISO 13849 risk graph: S, F and P give the required PL.
- 3
Set architecture and category
Model input, logic and output channels and choose the category.
- 4
Enter MTTFd, DCavg and CCF
Add component data; MSA calculates PFHd and the achieved PL.
- 5
Verify, or assign SIL
Compare achieved PL with PLr, or assign and verify SIL per IEC 62061.
MSA · Safety function SF-03 · ISO 13849
Risk graph → PLr
SS2 serious
FF2 frequent
PP1 possible
PLrd
Architecture · Category 3
I · Door switch
→L · Safety relay
→O · Contactors
MTTFd
62 y
High
DCavg
92 %
Medium
CCF
75 pts
Pass
PFHd2.3 × 10⁻⁷ /h
Achieved PL d ≥ PLr d✓ Verified
MSA · Safety function SF-07 · IEC 62061
Se
3
Fr
5
Pr
3
Av
3
Class CI = 11 → requiredSIL 2
| SS1 Sensor | 4.1 × 10⁻⁸ |
| SS2 Logic | 1.0 × 10⁻⁸ |
| SS3 Actuator | 9.6 × 10⁻⁸ |
| PFH total | 1.5 × 10⁻⁷ |
SIL 2 achieved ✓
Illustrative screen. Values are example data.
See it on your own machine
Bring a recent project. We’ll walk through it in MSA.