231-A083

Access Safety Input Status

Navigate to MOD > System > Safety > Input Status to view real-time status of all safety inputs in CC2 (second safety loop).

Use the live display to identify which specific input remains high during normal operation

Physical Inspection of Safety Devices

Inspect all door contacts, keylock switches, and E-stop buttons connected to CC2. Check for mechanical binding, contamination, or visible damage.

Ensure machine is in safe state and follow LOTO procedures before inspecting safety devices

Electrical Continuity Check

With power off, measure continuity across safety contacts. Normally closed contacts should show 0 ohms when closed, infinite when open.

Check wiring at X118/X119 safety connector terminals for loose connections or corrosion

Replace Faulty Safety Component

Replace the identified faulty safety device and verify proper wiring connections to the TNC safety inputs.

Safety devices must be identical part numbers or approved equivalents to maintain safety certification

Identify Affected Safety Circuit

Check TNC diagnostic display at MOD > Diagnosis > Safety to identify which CC2 input channel shows permanent high signal during dynamic test.

Note the specific input number (e.g., CC2.SI1, CC2.SI2) for targeted troubleshooting

Disconnect Safety Input Wiring

Power down and disconnect the safety input connector at X118/X119. Measure insulation resistance between conductors and to ground using 500V megohmmeter.

Verify zero energy state before disconnecting safety circuits

Trace Wiring Path

Follow the affected safety circuit wiring from TNC connector through cable chains, junction boxes, and to end devices looking for pinched, cut, or damaged cables.

Pay special attention to areas where cables flex or pass through metal panels

Repair or Replace Damaged Wiring

Repair damaged wiring using appropriate safety-rated cable and connectors. Ensure proper routing and strain relief to prevent future damage.

Use only safety-rated cable (Category 3/4) for safety circuit repairs

Verify Safety Module Status

Check MOD > System > Safety > Module Status for any hardware fault indicators on the CC2 safety input module.

Look for red status indicators or fault codes specific to the safety input processing

Perform Safety System Self-Test

Execute the built-in safety system diagnostic via MOD > Diagnosis > Safety > Self Test to isolate hardware vs. configuration issues.

Self-test will temporarily disable safety functions - ensure area is clear

Check Safety Module Connections

Inspect internal safety module connections and ribbon cables within the TNC cabinet for proper seating and signs of corrosion or damage.

Reseat all safety module connectors even if they appear secure

Replace Safety Input Module

If hardware fault is confirmed, replace the CC2 safety input module following Heidenhain service procedures and reconfigure safety parameters.

Safety module replacement requires factory authorization and safety system re-commissioning

Review Safety Configuration

Access MOD > System > Safety > Configuration and verify CC2 input assignments match actual wiring and safety device types.

Compare current configuration with machine documentation and previous backup files

Check Dynamic Test Parameters

Verify safety test timing parameters are within specification (test window = 100ms, test interval ≤ 1.5min) in the safety configuration menu.

Do not modify safety timing parameters without proper authorization

Validate Input Type Settings

Ensure each CC2 safety input is configured for correct device type (NC contact, NO contact, keylock, etc.) matching the physical installation.

Mismatched input types can cause dynamic test failures even with properly functioning hardware

Restore Known Good Configuration

If configuration errors are found, restore from a known good backup or reconfigure according to machine safety documentation.

Safety configuration changes require validation testing and may need safety authority approval

Check System Performance

Monitor CPU utilization at MOD > Diagnosis > System > Performance and look for excessive load during safety test cycles.

Normal CPU load should be <80% during safety test execution

Review Active Background Tasks

Check for excessive PLC program complexity, high-frequency interrupt routines, or communication tasks that may interfere with safety timing.

Modifying PLC programs may affect machine operation - document all changes

Clear System Memory

Perform controlled restart of TNC system to clear any memory fragmentation or temporary performance issues affecting real-time operation.

Save all programs and parameters before restart

Update TNC Software

Check for available software updates that may address known timing or performance issues with safety system operation.

Software updates may require safety system re-commissioning and validation