231-4003

Visual Inspection of All E-Stop Buttons

Check all emergency stop buttons on the machine panel, pendant, and any auxiliary stations. Look for buttons that appear pressed in or twisted to the locked position.

Do not attempt to force stuck buttons - they may be mechanically damaged

Reset Emergency Stop Buttons

Twist or pull each E-stop button to the released position. Listen for the distinctive 'click' sound indicating proper mechanical reset.

On older machines, E-stop buttons may require a quarter-turn clockwise after pulling out

Verify TNC Safety Status

Access MOD function and navigate to system information to check emergency stop status. The display should show 'E-STOP inactive' when properly reset.

Use softkey sequence: MOD > System Info > Safety Status to verify E-stop circuit continuity

Check Safety Relay LED Indicators

Open electrical cabinet and locate the safety relay module (typically Pilz PNOZ or similar). Check LED status indicators - green should be lit when E-stop circuit is complete.

Ensure main power is locked out before opening electrical cabinet

Measure 24VDC Supply to Safety Module

Using a multimeter, verify 24VDC is present at the safety relay input terminals. Check both positive and negative supply rails for proper voltage.

Typical safety modules require 20-28VDC to operate properly - anything below 20V will cause malfunction

Test Safety Relay Output Contacts

With E-stop buttons released, measure continuity across the safety relay output contacts that feed the TNC emergency stop input (typically terminals 13-14 and 23-24).

Safety relays use dual-channel outputs - both channels must show continuity for TNC to accept E-stop as inactive

Inspect TNC X1 Connector Wiring

Check the emergency stop wiring connections at the TNC's X1 connector. Look for loose, corroded, or damaged wire terminations at pins typically labeled 'E-STOP' or 'NOT-AUS'.

Power down TNC before disconnecting X1 connector to prevent damage to control inputs

Verify Wire Continuity to Safety Relay

Using a multimeter, test continuity from TNC X1 emergency stop input pins back to the safety relay output terminals in the electrical cabinet.

Heidenhain TNC typically uses pins 6 and 7 on X1 connector for emergency stop input - consult your specific TNC model documentation

Check for Proper Signal Voltage at TNC

With safety circuit active (E-stop released), measure 24VDC at the TNC emergency stop input pins. Voltage should be stable and within 20-28VDC range.

Use TNC diagnostic screen to monitor real-time emergency stop input status while measuring voltages

Access TNC Safety Parameters

Enter MOD mode and navigate to machine parameters. Access the safety-related parameters section (typically MP7300-MP7399 range depending on TNC model).

Use search function in parameter list by typing 'EMERGENCY' or 'SAFETY' to quickly locate relevant parameters

Verify Emergency Stop Test Configuration

Check parameter settings for emergency stop test interval and monitoring method. Ensure MP7380 (E-stop test enable) is set correctly for your machine configuration.

Changing safety parameters may require machine manufacturer authorization codes

Reset Safety Test Sequence

Clear any pending safety test flags by accessing the safety reset function in MOD menu. This forces the TNC to restart its emergency stop verification sequence.

After parameter changes, cycle TNC power completely to ensure new safety settings take effect