
PLC Sequence Designer and Safety Logic Validator
Design & validate industrial control sequences with safety interlocks
What You Can Do
You can rapidly design PLC sequences, document control logic with safety interlocks, and validate fault-handling behavior before deploying to production. Claude helps you define state machines, verify timing constraints, and ensure compliance with industrial safety standards like IEC 61508. Get comprehensive sequence diagrams, ladder logic templates, and safety case documentation all from natural language descriptions of your control requirements.
Features
Convert control requirements into detailed state machines with clear transitions and guards
Automatically identify critical paths and add appropriate safety interlocks to prevent hazardous states
Design fault handlers for common failure modes (sensor failures, communication loss, actuator stickiness)
Verify that all timing requirements (dwell times, debounce intervals, watchdog timeouts) are documented and consistent
Generate pseudocode and template logic suitable for IEC 61131-3 compliant PLC environments
Produce state diagrams, truth tables, hazard matrices, and safety case summaries
Validate sequences against common industrial patterns (push-to-start, dual-channel shutdown, safe state fallbacks)
Example Output
Input Request:
"Design a safety interlock sequence for a press with dual pushbuttons, pressure sensors, and emergency stops. Must reach safe state within 200ms."
Output Artifacts:
State Machine:
IDLE → ARMED (both pushbuttons pressed, sensor ≥ 50 bar)
→ ENGAGE → CYCLE_ACTIVE → RETRACT → IDLE
Emergency path: any state → E_STOP → SAFE_STOP → IDLE (≤200ms)
Safety Interlock Rules:
- No transition to ENGAGE if either pushbutton released
- No transition if pressure sensor < 50 bar (prevents partial engagement)
- E-stop must bring arm to safe position within 200ms
- Watchdog: pressure must drop within 500ms after RETRACT; trigger alarm if timeout
Fault Handlers:
- Sensor failure: Monitor for stuck/implausible readings → trigger safe state
- Communication timeout: Revert to safe state on sensor feed loss
- Actuator stickiness: Log timeout on retract; alert operator
Validation Report: ✓ All critical paths covered | ✓ Timing constraints feasible | ✓ Dual-channel logic verified | ⚠ Recommend independent hardwired E-stop circuit
What's Included
- SKILL.md: PLC sequence design methodology and validation workflows
- Sequence template: Markdown template for documenting state machines and transitions
- Safety interlock checklist: Guide to common interlocks and when to apply them
- Fault mode worksheet: FMEA-style template for identifying and handling failure modes
- Timing constraint tracker: Checklist for dwell times, debounce intervals, and watchdog timeouts
- Compliance reference: Quick reference for IEC 61508 and IEC 61131-3 requirements
Who It's For
- Controls engineers — Design robust sequences without manual state diagram work
- Safety engineers — Review sequences for compliance and interlock completeness
- PLC programmers — Generate ladder logic requirements and template pseudocode
- Manufacturing engineers — Validate control logic for new equipment or process changes
- Automation consultants — Document and review client sequences quickly
Best For
- Designing new industrial control sequences from functional requirements
- Adding safety interlocks to existing processes
- Validating fault-handling behavior before commissioning
- Documenting control logic for compliance audits and regulatory review
- Teaching control design patterns and safety best practices to junior engineers







