230-0043

Access PLC diagnostic function

Press MOD key, select 'Diagnose PLC' or 'PLC Diagnostics', navigate to Inputs section and locate the reference switch input for the affected axis (typically labeled as REF X, REF Y, etc. on X1 inputs)

On iTNC 530/TNC 620/640, use the PLC > Diagnostic tab to see real-time input states with better visualization

Manually actuate reference switch

With machine power on but axis not moving, manually push the reference cam against the reference switch. Observe if the corresponding input in PLC Diagnostics changes state from 0 to 1 (or FALSE to TRUE)

Ensure safe access to reference switch area - use lockout/tagout procedures if entering machine envelope

Check reference cam alignment

Verify the reference cam is properly mounted, not bent or damaged, and positioned to actuate the switch with sufficient overlap (typically 5-10mm of engagement). Check mounting screws are tight

Use a feeler gauge to verify consistent switch actuation gap - should be 0.5-2mm depending on switch type

Inspect switch and wiring

Check reference switch for physical damage, verify wiring connections at switch and X1 terminal strip are secure. Measure voltage at switch input (typically 24VDC) with multimeter

Common wire colors: Brown=+24V, Blue=GND, Black=Signal - verify against your machine's wiring diagram

Access axis machine parameters

Press MOD key, enter machine parameter password, select 'Machine Parameters' > 'Axis-specific parameters' > select affected axis. Navigate to MP1000 series parameters

Document original parameter values before making changes - incorrect settings can cause dangerous machine behavior

Verify MP1000 and MP1001

Check MP1000 (direction for moving off reference cam) and MP1001 (search direction for reference mark). Common setting: MP1000=0 (positive direction), MP1001=1 (negative direction) for typical setup

If axis homes to positive end of travel, MP1000 is usually negative (-1) and MP1001 positive (1)

Check MP1010 reference mode

Verify MP1010 matches encoder type: 0=reference switch only, 1=reference switch + distance-coded marks, 2=absolute encoder. Most linear axes with single reference cam use MP1010=0

For EnDat absolute encoders, MP1010 should be 2; for HEIDENHAIN distance-coded (DIADUR), use mode 1

Verify MP1002 reference offset

Check MP1002 (offset from reference mark to machine zero). This should be set to the calibrated distance measured during machine commissioning. Incorrect value won't cause alarm but indicates parameter corruption

Review machine commissioning documentation for original MP1002 values - store these in a safe location

Check encoder error log

Press MOD > 'Error Messages' > review log for encoder-specific errors (220-series or 280-series alarms) that occurred around the same time as the 230-0043 alarm. Note any encoder communication errors

Look for alarms 220-0002 (position error) or 280-xxxx (encoder errors) which indicate encoder signal issues

Inspect encoder cable and connections

Power down control, verify encoder cable connections at motor/encoder and at TNC X22-X24 encoder inputs. Check for damage, bent pins, or contamination. Verify cable shield is connected at control side only

Power off control before disconnecting encoder cables - hot-plugging can damage encoder interface electronics

Clean encoder scale and reading head

For exposed linear scales, clean the scale and reading head using lint-free cloth with isopropyl alcohol. Check scanning gap with appropriate feeler gauge (typically 0.3-0.5mm for HEIDENHAIN LIC/LIF encoders)

HEIDENHAIN supplies specific scanning gap gauges - verify gap across entire travel range, not just at reference point