21610

Check Emergency Stop Circuit

Navigate to HMI Diagnostics > PLC > Status and verify emergency stop chain status in safety PLC interface signals.

Never bypass safety interlocks - resolve root cause of safety violation

Verify Door/Guard Positions

Check all machine guards and doors are properly closed and their limit switches are functioning in PLC input diagnostics.

Use PLC variable table to monitor safety input states in real-time

Test Safety Device Continuity

Use multimeter to verify 24VDC continuity through complete safety chain from PLC safety inputs to feed enable output logic.

Follow LOTO procedures when testing electrical circuits

Examine PLC Enable Logic

Access STEP7/TIA Portal and review PLC program blocks controlling feed enable outputs, focusing on DB380x write operations.

Look for recently modified program blocks that may have introduced logic errors

Monitor Enable Signal Path

Use PLC online monitoring to trace signal flow from axis ready inputs through enable logic to final DB380x.DBX12.0 output.

Create force table to temporarily override intermediate signals for isolation testing

Verify NCK Interface Mapping

Check that PLC DB380x structure matches NCK interface requirements using HMI Service > NCK > Interface signals display.

Incorrect DB structure mapping can cause intermittent enable failures

Check Drive Status LEDs

Inspect all servo drive front panel LEDs for fault indications (red) or not-ready states (yellow/orange flashing).

S120 drives show detailed status on integrated display - check for specific fault codes

Verify Drive Enable Chain

Navigate to HMI Diagnostics > Drives and confirm all axes show 'Drive Ready' status and no active drive alarms.

Clear drive faults before attempting to restore feed enable

Test Drive Communication

Use STARTER software to verify PROFIBUS/PROFINET communication to all drive units and check cyclic data exchange.

Monitor MD36300 (axis enable signals) to verify NCK-drive communication integrity

Check PLC Communication Status

Navigate to HMI Service > PLC > Communication and verify active connection status and cyclic data exchange rates.

Look for communication timeout counters or error statistics in PLC diagnostics

Verify Interface DB Consistency

Compare NCK interface DB structure with PLC DB380x using HMI Service > NCK > PLC Interface to ensure data consistency.

Mismatched DB versions can cause sporadic communication failures

Test Communication Recovery

Perform controlled PLC stop/start cycle and monitor interface signal restoration using NCK alarm buffer and PLC diagnostics.

Use MD11210 (PLC interface timeout) to adjust communication monitoring if needed

Verify Axis Enable Parameters

Check MD36300 for affected axis using HMI Service > NCK > Machine Data to confirm proper enable signal source configuration.

MD36300 bit assignments must match PLC DB380x output bit mapping exactly

Review Feed Enable Source

Examine MD36310 setting to verify NCK is looking for feed enable from correct PLC interface signal location.

Changing these parameters requires NCK restart and may affect other axes

Compare Working Axis Configuration

Compare machine data settings between affected axis and properly functioning axes to identify configuration discrepancies.

Use NCK machine data comparison tool to quickly identify parameter differences