Active Interlock Systems

Overview

The driver can handle active interlock signals from external safety systems. This allows integration with electronic safety controllers, PLCs, and other active safety devices.

Active Interlock Signal Requirements

Signal Specifications

Parameter	Requirement
Signal Type	Active Low
Low Level (Disabled)	0V
High Level (Enabled)	5V
Maximum Voltage	5V
Logic	Fail-safe (high = safe)

Signal Logic

Active Low Configuration

0V (LOW) → Interlock activated → Laser DISABLED
5V (HIGH) → Interlock normal → Laser ENABLED

This is a fail-safe configuration:

Loss of signal (0V) disables the laser
Signal must be actively maintained (5V) for operation

Connection Instructions

Basic Wiring

External Safety Controller
        │
        ├─── Signal Output (0-5V) ──→ IL+
        │
        └─── Ground (Reference) ──→ IL-

Ground Reference

Use common ground between driver and external controller
Ensure clean ground connection
Avoid ground loops

Integration with External Systems

PLC Integration

    PLC Output
    (0-5V NPN/PNP)
         │
         ├─── Output+ ──→ IL+
         │
         └─── Common  ──→ IL-

Safety Controller Integration

Safety Relay Output
(Fail-Safe Output)
         │
         ├─── NO Contact ──→ IL+
         │     (with 5V)
         └─── Common ──→ IL-

Emergency Stop Integration

E-Stop Controller
         │
    Safety Output
    (Active Low)
         │
         ├─── Signal ──→ IL+
         └─── GND ──→ IL-

Higher Voltage Systems

Using Relays

High Voltage Signal ──→ Relay Coil
                         │
                    Relay Contact
                         │
                    ├─── 5V Supply
                    │
                    ├─── Contact NO ──→ IL+
                    │
                    └─── GND ──→ IL-

Advantages:

✅ Complete galvanic isolation
✅ Protection from overvoltage
✅ Compatible with any input voltage
✅ Fail-safe operation possible

Using Optical Couplers

High Voltage Signal
        │
    Optocoupler
    Input Side
        │
        ↓ (optical)
        │
    Optocoupler
    Output Side
        │
        ├─── Output (0-5V) ──→ IL+
        │
        └─── GND ──→ IL-

Advantages:

✅ Galvanic isolation
✅ Fast response time
✅ Compact solution
✅ EMI protection

Combining Passive and Active Interlocks

You can combine both passive and active interlock systems:

Hybrid Configuration

For systems requiring both mechanical switches AND electronic safety signals:

                    Passive Loop
IL+ ──┬─── [Door Switch] ───┬─── IL-
      │                     │
      └─── Active Signal ───┘
         (from controller)

Testing Active Interlock Systems

Functional Test

Apply 5V signal to interlock input
Verify laser operation (should be enabled)
Reduce signal to 0V
Verify immediate shutdown (within microseconds)
Check Interlock LED (should be flashing)
Restore 5V signal
Verify recovery (depends on operating mode)

Signal Quality Check

Measure signal voltage levels
Check for noise and ripple
Verify rise/fall times
Test under load conditions

Common Active Interlock Sources

Source	Typical Application
PLC Safety Output	Industrial automation
Safety Light Curtain	Personnel protection
Area Scanner	Room safety monitoring
Safety Controller	Machine safety systems
Remote E-Stop	Distributed safety
Beam Shutter Sensor	Optical path protection
Access Control System	Room access monitoring

Signal Specifications

Recommended Signal Characteristics

Parameter	Value
Rise Time	<1ms
Fall Time	<1ms
Noise Immunity	>1V
Source Current	>1mA

Troubleshooting

False Triggers

Symptom: Interlock activates unexpectedly

Possible Causes:

Electrical noise on signal line
Ground potential differences
Insufficient signal voltage

Solutions:

Use shielded cable
Ensure proper grounding
Verify signal voltage levels
Add filtering if necessary

Delayed Response

Symptom: Slow interlock response

Possible Causes:

Slow rise/fall time
Cable capacitance
Weak signal source

Solutions:

Use proper cable
Check signal source capability
Minimize cable length

Best Practices

✅ Always verify voltage levels are within 0-5V range
✅ Use galvanic isolation for external high voltage systems
✅ Ensure common ground reference
✅ Test interlock function regularly
✅ Document the interlock circuit completely
✅ Label all connections clearly
✅ Use fail-safe logic (active high for normal operation)