Overview
This lecture explains the engineering process for a failsafe safety application using Siemens S7-1200 components, covering both hardware configuration and safety programming in TIA Portal.
Hardware Configuration
- The system uses a CPU 1212 FC and two failsafe signal modules: FDI (input) and FDQ (output).
- Begin a new TIA Portal project and drag the CPU 1212 FC into the network editor.
- Insert failsafe input and output modules by drag-and-drop or double-click; modules fill the next free slot.
- Set module and channel parameters for the FDI module based on device connections (emergency stop, safety switches).
- Decide on one or two-channel evaluation, encoder supply (internal/external), and adjust discrepancy time as needed.
- For emergency stop: select two-channel evaluation (1 out of 2), 100ms discrepancy time, internal encoder supply.
- For safety door switch: use two-channel evaluation, 100ms discrepancy, external supply (sensor provides a safe signal).
- Default parameters for channel acknowledgment or input filter usually do not need changes.
- Enable short-circuit protection for all 16 channels.
- Assign variable names for symbolic addressing, e.g., "dub" for emergency stop, "safety door" for safety door input.
- For FDQ module (output), keep default parameters and assign variable names like "start/stop" and "AK" (acknowledgement).
Safety Program Creation
- The project includes a Safety Administration Editor for managing the safety program.
- OB 123 calls the main safety function block (FB) which contains the safety logic.
- In the safety editor, set cycle time, priority, warning, and maximum cycle time.
- Use certified safety function blocks (e-stop, two-hand, muting, feedback loop, safety door).
- Drag the e-stop block to the first network and connect its import (e.g., "dub" variable).
- ACK NEC parameter requires an acknowledgment when the e-stop is used; connect ACK input.
- Define a static variable for the e-stop output for logic interconnection.
- Repeat process for safety door block, connecting relevant variables and acknowledgment.
- Insert a memory element to handle safety shutdown logic for motor starters.
- Logic: start button turns on safely; stop button or open safety door turns off safely.
- System safely switches off on device/channel error; affected module is passivated.
- Global acknowledgment for all F modules via ACK GL, connected to the acknowledgment button.
- Compile the safety program and observe unique offline signatures for hardware and program modifications.
Key Terms & Definitions
- Failsafe Controller — A controller designed to maintain safety even in the event of a fault.
- FDI Module — Failsafe digital input module for safety signal acquisition.
- FDQ Module — Failsafe digital output module for actuating safety-related outputs.
- Discrepancy Time — Maximum allowed difference between input channels during two-channel evaluation.
- 1 out of 2 Evaluation — Safety logic where two input channels must both indicate safe status.
- ACK (Acknowledgment) — A confirmation input required after certain events, such as an emergency stop.
- Safety Administration Editor — Project tool for managing safety program logic and settings.
- Offline Signature — Unique identifier for hardware and program state, used for traceability.
Action Items / Next Steps
- Complete FDI module configuration by assigning all variable names.
- Compile the project and check the offline signatures for future reference.
- Save and download the configured project to the S7-1200 CPU.