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Safety.md

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Safety Components

SafetyBase

Abstract base for TwinCAT Safety function blocks. Reads ST_SafetyStateDiag from the TwinSAFE PLC via hardware mapping, drives OK/Error/Busy status, and supports simulation mode for commissioning without safety hardware.

Extends: CyclicComponent
Implements: I_SafetyBase

Interface

Member Type Description
FB_Init(Name) Constructor Standard component name
OK BOOL (Get) TRUE when the safety function is in a safe, running state
Error BOOL (Get) TRUE on a safety fault
ErrorId UDINT (Get) Error code
Busy BOOL (Get) TRUE while an operation is in progress
Simulated BOOL (Get/Set) Bypasses hardware check; useful during commissioning without safety hardware
ResetFunction I_SafetyReset (Set) Optional reset handler called by Reset()
Reset() Method Executes the registered reset function
SimulateSafetyState(Value) Method Injects a simulated state value into InfoData.State
SimulateSafetyDiag(Value) Method Injects a simulated diagnostic value into InfoData.Diag
CyclicLogic() Method Checks hardware mapping; drives reset function each scan

Notes

  • InfoData must be linked AT %I* to the TwinSAFE PLC's state/diagnostic output in the hardware configuration.
  • If not mapped and Simulated = FALSE, a trace warning is logged once and the FB runs without diagnostics.

SafetyAndOrFB

Extends SafetyBase. Sets OK = TRUE when InfoData.State = E_SafetyOrAnd_State.Run. Use this for TwinSAFE AND/OR gate function blocks.

Extends: SafetyBase

Example

VAR
    EStopGroup : SafetyAndOrFB('EStopGroup');
END_VAR

EStopGroup.CyclicLogic();

IF EStopGroup.OK THEN
    // All E-Stop inputs are clear, safe to operate
END_IF

// Simulation (no hardware needed)
EStopGroup.Simulated := TRUE;
EStopGroup.SimulateSafetyState(E_SafetyOrAnd_State.Run);

SafetyModule

A specialised Module that acts as a container for all safety-related SafetyBase components. Manages the TwinSAFE PLC connection via CoE, reads FSoE address and project CRC at startup, provides aggregate OK/Error status across all registered safety components, and implements a timed reset sequence for TwinSAFE.

Extends: Module
Implements: I_SafetyModule

Interface

Member Type Description
FB_Init(Name) Constructor Registers internal CoeDevice with the module
OK BOOL (Get) TRUE when all registered safety components report OK
Error BOOL (Get) TRUE if any registered component has an error
ErrorId UDINT (Get) Error ID from the first faulted component
Busy BOOL (Get) TRUE while a reset sequence is running
Simulated BOOL (Get/Set) Propagates simulation mode to all child components via SetSafetySimulationVisitor
AddSafetyComponent(Component) Method Registers an I_SafetyBase component with the module
Reset() Method Triggers a timed TwinSAFE reset sequence (250 ms delay)
SafetyAddressInfo REFERENCE TO ST_SafetyAddressInfo (Get) FSoE address, serial number, and CRC read during init
SafetyPlcCoE I_CoeDevice (Get) CoE device used to communicate with the TwinSAFE PLC

Hardware Requirements

The following variables must be linked AT %I* in the hardware configuration:

  • SafetyPLC_WcState — Working counter state of the safety PLC frame
  • SafetyPLC_AmsAddr — AMS address of the TwinSAFE PLC

Example

VAR
    Safety     : SafetyModule('Safety');
    EStop      : SafetyAndOrFB('EStop');
    LightCurtain : SafetyAndOrFB('LightCurtain');
END_VAR

Safety.AddSafetyComponent(EStop);
Safety.AddSafetyComponent(LightCurtain);

// Each scan
Safety.CyclicLogic();
EStop.CyclicLogic();
LightCurtain.CyclicLogic();

IF NOT Safety.OK THEN
    // A safety function is not in Run state
END_IF

// Reset after a safety event is cleared
Safety.Reset();

SafetyResetPulse

Generates a pulsed reset signal for TwinSAFE function blocks. Implements I_SafetyReset and is typically injected into a SafetyBase via ResetFunction.

Interface

Member Type Description
Execute() Method Triggers the reset pulse
CyclicLogic() Method Must be called each scan to manage the pulse timing