TwinSAFE Safety Configuration Guide

Version: APR-2026.01 | TwinCAT: 3.1 Build 4024.65

Safety architecture for APR dual-axis linear motor system.

Overview

This skill covers the TwinSAFE safety system configuration for the APR system, including safety hardware selection, STO (Safe Torque Off) implementation, and safety PLC programming.

Safety Hardware

Terminal	Function	Description
EL6900	TwinSAFE Logic	Safety PLC, executes safety program
EL1904	Safety Digital Input	4-channel, dual-channel evaluation
EL2904	Safety Digital Output	4-channel, SIL3/PLe capable

Safety Architecture

code

┌─────────────────────────────────────────────────────────────────┐
│                    TwinSAFE Safety Loop                          │
├─────────────────────────────────────────────────────────────────┤
│                                                                  │
│  ┌──────────┐     ┌──────────┐     ┌──────────┐     ┌─────────┐ │
│  │ E-STOP   │────►│ EL1904   │────►│ EL6900   │────►│ EL2904  │ │
│  │ (Ch1+Ch2)│────►│ DI 1+2   │     │ Safety   │     │ DO 1-4  │ │
│  └──────────┘     └──────────┘     │ Logic    │     └────┬────┘ │
│                                    │          │          │      │
│  ┌──────────┐     ┌──────────┐     │          │          │      │
│  │ Light    │────►│ EL1904   │────►│          │          ▼      │
│  │ Curtain  │────►│ DI 3+4   │     │          │     ┌─────────┐ │
│  │ (OSSD)   │     └──────────┘     └──────────┘     │ E1 STO  │ │
│  └──────────┘                                       │ STO1/2  │ │
│                                                     └─────────┘ │
└─────────────────────────────────────────────────────────────────┘

EL1904 Input Configuration

Channel Assignment

Channel	Signal	Type	Description
DI 1	E-STOP Ch1	NC Contact	Emergency stop channel 1
DI 2	E-STOP Ch2	NC Contact	Emergency stop channel 2
DI 3	Light Curtain OSSD1	PNP 24V	Safety output 1
DI 4	Light Curtain OSSD2	PNP 24V	Safety output 2

Wiring Requirements

•Dual-channel wiring for E-STOP (redundancy)
•Light curtain OSSD: PNP, 24VDC
•Cable shield grounded at one end
•Max cable length: 100m

EL2904 Output Configuration

Channel Assignment

Channel	Signal	Load	Description
DO 1	STO1 Axis A	E1 Drive	Safe Torque Off Ch1
DO 2	STO2 Axis A	E1 Drive	Safe Torque Off Ch2
DO 3	STO1 Axis B	E1 Drive	Safe Torque Off Ch1
DO 4	STO2 Axis B	E1 Drive	Safe Torque Off Ch2

Wiring to E1 Drive

code

EL2904 DO1 ────────────► E1 Drive Axis A STO1
EL2904 DO2 ────────────► E1 Drive Axis A STO2

EL2904 DO3 ────────────► E1 Drive Axis B STO1
EL2904 DO4 ────────────► E1 Drive Axis B STO2

EL6900 Safety Program

Function Blocks

FB	Purpose
SF_EmergencyStop	E-STOP dual-channel evaluation
SF_ESPE	Light curtain (ESPE) evaluation
SF_SafeStop1	SS1: controlled stop then STO
SF_EDM	External Device Monitoring

Safety Logic Example

iecst

PROGRAM SafetyPLC
VAR
    // Inputs from EL1904
    bEStop_Ch1      : BOOL;
    bEStop_Ch2      : BOOL;
    bLightCurtain1  : BOOL;
    bLightCurtain2  : BOOL;
    bResetButton    : BOOL;

    // Outputs to EL2904
    bSTO1_AxisA     : BOOL;
    bSTO2_AxisA     : BOOL;
    bSTO1_AxisB     : BOOL;
    bSTO2_AxisB     : BOOL;

    // Function Blocks
    fbEStop         : SF_EmergencyStop;
    fbLightCurtain  : SF_ESPE;
END_VAR

// E-STOP evaluation
fbEStop(
    Activate := TRUE,
    S_EStopIn := bEStop_Ch1 AND bEStop_Ch2,
    S_StartReset := bResetButton,
    S_AutoReset := FALSE,
    Reset := bResetButton
);

// Light curtain evaluation
fbLightCurtain(
    Activate := TRUE,
    S_OSSD1 := bLightCurtain1,
    S_OSSD2 := bLightCurtain2,
    S_StartReset := bResetButton,
    Reset := bResetButton
);

// Combined safety output
bSTO1_AxisA := fbEStop.S_EStopOut AND fbLightCurtain.S_ESPE_Out;
bSTO2_AxisA := bSTO1_AxisA;
bSTO1_AxisB := bSTO1_AxisA;
bSTO2_AxisB := bSTO1_AxisA;

Safety Response Times

Component	Response Time
EL1904 Input	< 4 ms
EL6900 Logic	< 6 ms
EL2904 Output	< 4 ms
E1 STO Response	< 10 ms
Total System	< 24 ms

Safety Functions

STO (Safe Torque Off)

•Removes torque from motor
•Does NOT control position
•Used for: E-STOP, light curtain intrusion

SS1 (Safe Stop 1)

•Controlled deceleration
•Then activates STO
•Used for: Graceful safety stop

SBC (Safe Brake Control)

•Controls mechanical brake
•Activates after STO
•Prevents gravity fall (vertical axes)

Safety Solution Architecture (4 Frameworks)

The APR safety system integrates components from multiple frameworks:

Framework Integration

•Beckhoff TwinSAFE - Core safety PLC and I/O
•HIWIN E1 STO - Drive-integrated safety
•Keyence GL-V - Safety light curtain
•ISO 13849 / IEC 62443 - Safety standards compliance

Safety Zones

code

┌─────────────────────────────────────────┐
│              Safety Zone A               │
│  ┌─────────────────────────────────┐    │
│  │        Light Curtain Zone       │    │
│  │   (GL-VM72HP, 1440mm height)    │    │
│  └─────────────────────────────────┘    │
│                                          │
│  ┌─────────────────────────────────┐    │
│  │       Motion Hazard Zone        │    │
│  │  (LMSA13L, 4.2m travel, 9.7m/s) │    │
│  └─────────────────────────────────┘    │
└─────────────────────────────────────────┘

Commissioning Checklist

• Verify EL1904 input wiring (dual-channel)
• Configure EL6900 safety program
• Link EL2904 outputs to E1 STO inputs
• Test E-STOP function (both channels)
• Test light curtain response
• Measure actual response time
• Verify reset button function
• Document safety validation

Safety Categories

Safety Level	Application
SIL 2 / PLd	Standard machine safety
SIL 3 / PLe	High-risk applications

TwinSAFE with EL1904/EL6900/EL2904 supports up to SIL 3 / PLe.

Available References

•references/framework-integration.md - ASCII blueprint integrating 4 safety frameworks
•references/github-hosting.md - APR_HiwinLMSA_SafetyGate GitHub hosting plan