Emergency Stop up to SIL 3 / PL e with Fail-Safe S7-1500
The solution integrates both the standard automation program and the safety program in one controller, allowing seamless interaction between process control and functional safety. Emergency Stop up to SIL 3 PL e…
Application Objective
The system is designed to safely shut down a machine during emergency conditions while achieving safety levels up to SIL 3 according to IEC 62061 or PL e according to ISO 13849-1.
System Architecture
The configuration includes:
- Fail-safe CPU S7-1516F
- Distributed ET 200SP fail-safe I/O
- Communication via PROFIsafe over PROFINET
The emergency stop is implemented using dual-channel wiring and redundant contactors to ensure safe shutdown even if one switching device fails.
Core Safety Functions
The application provides:
- Immediate shutdown when the emergency stop is pressed
- Restart prevention until reset and acknowledgement are completed
- Monitoring of contactor feedback circuits
- Fault detection and safe re-integration after errors
Functional Safety Concept
Functional safety ensures that safety-related systems respond correctly to faults and bring the plant into a safe state when required.
Safety performance is evaluated using:
- Safety Integrity Level (SIL)
- Performance Level (PL)
Engineering Implementation
The example includes the configuration of:
- F-CPU parameters and monitoring time
- Fail-safe digital inputs/outputs
- Channel diagnostics and short-circuit detection
- Data exchange between standard and safety programs
Operation Logic
Typical operation sequence:
- Acknowledge system
- Start machine
- Press emergency stop → machine switches off safely
- Reset and acknowledge before restart
Benefits of the Solution
- Integrated safety and automation in a single platform
- Faster diagnostics and fault localization
- Safety status is available directly in the standard PLC programme.
- No additional wiring synchronization required
Typical Industrial Use Cases
This safety architecture is suitable for:
- Production lines
- Packaging machines
- Conveyor systems
- Process plants requiring certified safety shutdown
- Machinery compliant with IEC / ISO safety standards
