230-01C3

Access PLC Status Display

Navigate to MOD > PLC > Status to monitor emergency stop relay states K1, K2 and timing parameters.

Use the oscilloscope function in PLC diagnostics to measure actual switching times

Measure Relay Switching Times

Check MC.RDY to I3 response time using TNC diagnostic functions - should be <200ms per Heidenhain safety specifications.

Only qualified personnel should work on safety circuits

Replace Emergency Stop Relay

Replace the identified defective relay with Heidenhain-approved safety relay maintaining same part number and safety rating.

Always replace relays in pairs to ensure matched switching characteristics

Verify Safety Circuit Timing

Perform complete emergency stop test cycle and verify all timing parameters meet TNC safety requirements in MOD > Machine > Safety.

Document all safety circuit modifications per local safety regulations

Isolate Emergency Stop Inputs

Disconnect ES.A and ES.B inputs at X1 connector and measure voltage - should read 0V when emergency stop is active.

Power down system before disconnecting safety circuit wiring

Trace Wiring for Short Circuits

Use multimeter to check continuity between ES.A/ES.B and +24V supply, checking all junction boxes and cable runs.

Check for pinched cables at cable carriers and worn insulation at bend points

Repair or Replace Damaged Wiring

Replace damaged cable sections maintaining proper safety-rated cable specifications and routing per Heidenhain installation manual.

Use only safety-rated cables meeting SIL3/PLe requirements

Verify Signal Integrity

Test emergency stop function multiple times and monitor ES.A/ES.B signals in PLC status display to confirm proper switching.

Perform both manual E-stop button test and automatic safety circuit test

Test Emergency Stop Button Operation

Activate emergency stop button while monitoring contact states in MOD > PLC > Inputs - contacts should switch cleanly without bouncing.

Listen for unusual clicking or grinding sounds indicating worn contacts

Measure Contact Resistance

With power off, measure contact resistance across emergency stop button terminals - should be <0.1 ohm closed, >1M ohm open.

Test both NC and NO contacts if button has dual contact blocks

Replace Emergency Stop Button

Install new emergency stop button maintaining same safety rating and contact configuration as specified in machine documentation.

Apply dielectric grease to contact terminals to prevent corrosion

Calibrate Safety Response Time

Perform emergency stop timing test through TNC safety diagnostics to verify response time meets <200ms requirement.

Complete safety validation required before returning machine to production

Verify External Circuit Integrity

Confirm all external emergency stop wiring and components test correctly before suspecting TNC internal failure.

Use a known-good emergency stop circuit from another machine for comparison testing

Check TNC Input Module Status

Access MOD > Diagnosis > Hardware to check I3 input module status and any internal fault codes.

TNC internal repairs require factory-trained technicians

Contact Heidenhain Service

Document all test results and contact Heidenhain technical support for TNC module diagnosis and potential replacement.

Have TNC software version, NC software number, and complete alarm history ready

Arrange TNC Module Service

Schedule TNC control module service or replacement through authorized Heidenhain service center maintaining all safety certifications.

Only use genuine Heidenhain replacement modules to maintain safety compliance