20001

Check Sensor Signal in PLC Diagnostics

Navigate to Diagnostics > PLC > I/O Status and monitor the tool clamped input signal while manually actuating the drawbar. Verify signal changes state.

Use HMI Service screen 'PLC Status' to view real-time I/O without entering service mode.

Inspect Sensor Physical Condition

Check proximity sensor for contamination, damage, or incorrect gap distance. Clean sensor face and verify 1-2mm gap to target when drawbar is fully retracted.

Ensure spindle is stopped and locked out before accessing sensor area.

Verify Sensor Power and Wiring

Measure 24VDC supply voltage at sensor connector and check continuity of signal wire to PLC input terminal using multimeter.

Check PLC input LED status - should illuminate when sensor activates.

Verify Tool Management Interface Settings

Check Parameters > Machine Data > MD11050 TOOL_MANAGEMENT_MASK bit assignment. Ensure bit for tool clamped signal matches PLC interface definition.

Bit 0 of MD11050 typically enables tool clamped monitoring - verify this matches your PLC program.

Check PLC Interface Signal Mapping

In PLC program, verify DB31.DBX interface signal for tool clamped (typically DB31.DBX1.1) is correctly mapped to physical input from proximity sensor.

Document original PLC program before making changes.

Test Interface Signal Response

Use PLC online monitoring to force the tool clamped interface bit and verify alarm 20001 clears, confirming NC-PLC communication path.

Use SINUMERIK Operate 'Service' screen to monitor interface signals in real-time during testing.

Check Current Monitoring Time Setting

Navigate to Parameters > Machine Data > Spindle and read MD11420 TOOL_CLAMP_TIME value. Note current setting in milliseconds.

Typical values range from 2000-5000ms depending on spindle hydraulic response time.

Measure Actual Clamping Time

Use stopwatch to time from M6 tool change command to sensor activation. Compare measured time to MD11420 setting.

Ensure adequate safety clearance when observing tool change operations.

Adjust Monitoring Time Parameter

Increase MD11420 value to 150% of measured clamping time. Reset system and test tool change operation to verify alarm clears.

Make incremental increases - excessive timeout values can mask actual mechanical problems.

Inspect Tool Holder Condition

Remove tool holder and check pull stud threads, taper surface, and retention knob for wear, damage, or contamination. Clean with appropriate solvent.

Use proper lifting techniques - tool holders can be heavy and have sharp edges.

Check Spindle Taper and Drawbar

Inspect spindle taper bore for damage, contamination, or foreign objects. Verify drawbar moves freely and pull stud threads engage properly.

Use spindle bore light and mirror to thoroughly inspect taper condition.

Test Drawbar Hydraulic Pressure

Verify hydraulic clamping pressure meets specification (typically 40-60 bar). Check for pressure drops that indicate internal leakage.

High pressure hydraulic system - follow lockout procedures before pressure testing.